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Bureau of Mines Information Circular/1982 



/(^d' 



Proceedings of Seminar on the Role 

of Overburden Analysis 

in Surface Mining, 

Wheeling, W. Va., May 6-7, 1980 

Sponsored by the American Council 
for Reclamation Research 
and the Bureau of Mines 

Compiled by D. G. Simpson and W. T. Plass 



^^ 



"'^N 




i UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 8863 r (^Ufv^Vec ^ (A-Mmes. ) . 



Proceedings of Seminar on the Role 
of Overburden Analysis 
in Surface Mining,, (f^g'd • Hk^:^^ vi,\l^,^ 
Wheeling, W. Va., May 6-7, 1980 

Sponsored by the American Council 
for Reclamation Research 
and the Bureau of Mines 

Compiled by D. G. Simpson and W. T. Plass 




UNITED STATES DEPARTMENT OF THE INTERIOR 
James G. Watt, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 




■^0. 



l^'^ 




'Wis pti'bli cation has been cataloged as follows: 



Seminar on the role of overburden analysis in surface min- 
ing (1980 : Wheeling, W. Va,). 

Proceedings of Seminar on the Role of Overburden Analysis 
in Surface Mining, Wheeling, W. Va., May 6-7, 1980. 

(Information circular / 8863) 

Includes bibliographical references. 

Supt. of Docs, no.: I 28.27:8863- 

1. Strip mining— Environmental aspects— Congresses. 2. Reclama- 
tion of land— Congresses. 3. Soils— Analysis— Congresses. I, Simp- 
son, D. G. (David G.). II. Plass, W. T. III. American Council for Rec- 
lamation Research. IV. United States- Bureau of Mines. V. Title. 
VI. Series: Information circular (United States. Bureau of Mines) ; 8863. 

-TN?95.U4 - [TD195.S75] 622s [622'.3l] 81-607049 AACR2 



CONTENTS 

Page 

Abstract 1 

Introduction 1 

The geologic distribution of pyrlte and calcareous naterial and its 
relationship to overburden sampling, by Frank T. Caruccio and 
Gwendelyn Geidel 2 

Overburden sampling and analysis, by Richard M, Smith and John C, 

Sencindiver 13 

Use of soil-overburden data in nine planning and development, by Vance 

P. Wirara and David S. Ralston 21 

Minesoil classification, by E. S. Lyle , Jr 38 



PROCEEDINGS OF SEMINAR ON THE ROLE OF OVERBURDEN ANALYSIS 
IN SURFACE MINING, WHEELING, W. VA., MAY 6-7, 1980 

Sponsored by the Americon Council for Reclamation Research 
and the Bureau of Mines 

Compiled by D. Gt Simpson^ and W. T. Plass^ 



ABSTRACT 

This Bureau of Mines publication contains the texts of the four papers 
presented at the May 6-7, 1980, seminar on the role of overburden analysis in 
surface raining. Coverage includes the geologic distribution of pyrite and 
calcareous material and its relationship to overburden sampling, overburden 
sampling and analysis, use of soil-overburden data in mine planning and 
development, and minesoil classification. 

INTRODUCTION 

One of the objectives of the American Council for Reclamation Research is 
to encourage communication between research scientists, regulatory agencies, 
landowners, and the surface mining industry. This seminar provided these 
groups with an opportunity to discuss a relevant problem relating to mining 
and reclamation. An interchange of theoretical and practical consideration^' 
resulted. 

The Bureau of Mines, through its Minerals Environmental Technology Pro- 
gram, conducts research to evaluate the environmental, hydrologic, engineer- 
ing, and economic factors associated with surface mining of coal. The overall 
objectives of this work are the development and implementation of cost- 
effective technology mitigating environmental impacts directly through the 
mining process. Implicit in these objectives is the requirement to assist the 
raining and research communities in technology transfer of state-of-the-art 
results for field application. In the interests of those goals, the Bureau 
of Mines cosponsored this seminar and its proceedings, which were edited and 
published by the Bureau of Mines. 



^Chief, Wilkes-Barre Field Office, Bureau of Mines, Wilkes-Barre, Pa. 
^Executive Secretary, American Council for Reclamation Research, Princeton, 
W. Va. 



THE GEOLOGIC DISTRIBUTION OF PYRITE AND CALCAREOUS MATERIAL 
AND ITS RELATIONSHIP TO OVERBURDEN SAMPLING 

by 

Frank T, Caruccio^ and Gwendelyn Geidel^ 



ABSTRACT 

Within the Appalachian bituminous coalfield, calcareous material within 
strata tends to occur as laterally pervasive deposits, whereas pyrite-enriched 
zones (higher sulfur pockets) commonly occur as highly localized deposits. 
This distribution pattern in itself could create difficulty in sampling the 
overburden of a coal mine to adequately assess the acid mine drainage poten- 
tial of the site. However, our simulated-weathering studies have shown that 
small quantities of calcareous materials radically suppress pyrite oxidation 
and dominate the acid mine drainage reactions. This phenomenon permits us to 
integrate the field-observed distribution patterns of pyrite and calcareous 
material and the results of the laboratory simulated-weathering studies into a 
matrix that outlines, in relative terras, the intensity of sampling that is 
necessary to identify the presence or absence of potentially acid-producing 
strata and the degree of confidence that can be expected, 

STATEMENT OF THE PROBLEM 

Rock Chemistry Disequilibria Associated 
With Land Perturbations 

Coal mines, road excavations, tunnels, foundation settings, and similar 
land perturbations commonly expose fresh rock and sediments to accelerated 
weathering conditions. In the process, the various minerals that comprise 
the strata physically and chemically decompose to weathering products that 
readily interact with water and affect the chemistry of the drainage forming 
at the site. However, the quality of the drainage that eventually emanates 
from the area is a result of the many complex interactions between the hydrol- 
ogy of the area (both pre- and post-excavation) , the geochemistry of the 
ground water regime, microbial catalysis, frequency of rainfall, reclamation 
techniques, and revegetion endeavors, in addition to the overburden chemistry. 
Within this complex geochemical system there are two mineralogic components 
that seem to have a dominating effect on the drainage chemistry; these are (1) 
the iron sulfides, occurring as troilite, marcasite, and pyrite, hereinafter 
collectively called pyrite, and (2) calcium, magnesium carbonates occurring as 
sparry calcite or calcium, magnesium carbonate cement in sandstones, micritic 
cementation in shales and sandstones, limestones and dolomites, etc, collec- 
tively called calcareous material, (Siderite is not included,) This paper 

'Associate professor of geology. Department of Geology, University of South 

Carolina, Columbia, S,C. 
^Research specialist. Department of Geology, University of South Carolina, 

Columbia, S.C, 



addresses the impacts that these minerals have on the mine drainage quality 
within the context of their dissimilar stratigraphic distributions. These two 
facets of the acid mine drainage problem are subsequently integrated into a 
scheme that could be used to enhance and facilitate overburden sampling. 

In the coal mine areas of the Eastern United States, exposed pyrites are 
commonly observed to oxidize to soluble iron sulfate salts, which hydrolyze to 
produce acidity. On the other hand, calcareous material, in contact with 
water, has the capability of producing alkalinity. The degree to which either 
or both of these water quality components is produced determines, to a large 
extent, the mine drainage quality that will eventually emanate from the mine 
site. Thus, an assessment of the potential of the mine to produce acidic, 
alkaline, or neutral drainage requires a knowledge of the occurrence and dis- 
tribution of pyrite and calcareous material within the stratigraphic sequence 
that will be disturbed by the mining operation. This information is usually 
obtained through overburden analyses. In this process cores or samples of the 
overburden are collected, and each distinct rock type that is identified is 
sampled and chemically analyzed for pyritic sulfur and calcareous material 
content. 

In this evaluation process a major problem exists, with regard to the 
sampling phase, as to the borehole spacing needs and the density of cores 
required to adequately define the presence or absence of pyrite and calcareous 
material within the overburden of a proposed strip mining operation. Due to 
economic considerations, the number of holes drilled must be kept to a mini- 
mum; yet using too few holes precludes valid sampling of the rock strata. To 
better understand the nature of this problem, a brief summary of the mechanics 
of acid mine drainage formation is in order. One of the objectives of over- 
burden analyses is to identify and predict the potential occurrence of an acid 
mine drainage problem. To identify a rock's potential to produce acidity or 
alkalinity requires not only the chemical analyses of the overburden but an 
understanding of the kinetics of acid and alkaline release as well. As will 
be shown, the variations in kinetics are related to the geologic distribution 
of pyrite and calcareous material and the problem of sampling. To be sure, 
acid-producing strata that can be easily separated in a mining operation 
are to be selectively handled and isolated from near-surface environments in 
order to minimize the environmental impact of the mine. On the other hand, 
potentially alkaline or neutral strata, with the physical weathering charac- 
teristics that retain plant nutrients and moisture, are best utilized as 
near-surface depressing to enhance revegetation efforts. 

The Acid Mine Drainage Problem 

Acid mine drainage, as the name implies, is an extremely acidic, iron- 
sulfate-rich drainage that forms when calcareous-deficient, pyrite-enriched 
strata are exposed to the atmosphere. Although this problem is associated 
with coal mines, in particular those located in the Appalachian area, it has 
also been reported in other areas where the land perturbation exposed pyritif- 
erous strata. In these situations, the pyrite oxidizes in the presence of 
humidity and oxygen to form soluble hydrous iron sulfates. Subsequent 



immersion by natural water movement dissolves these compounds, which, in the 
absence of alkalinity, hydrolyze to form acidic drainages. 

However, not all coal mines produce acidic drainages. Depending upon a 
variety of factors, neutral or alkaline drainages can form which may be dis- 
charged to the local drainage network with no deleterious effects on the ecol- 
ogy. In addition, the potential impact that acid drainage has upon the 
immediate environment is mitigated by the chemistry of the streams receiving 
the drainages. In turn, the stream chemistry reflects the mineralogic compo- 
sition of the adjacent strata, which, in turn, affects drainages, emanating 
from mines sited in these stratigraphic horizons. As an example, local geolo- 
gies containing substantial amounts of calcareous material generate streams 
that are strongly alkaline and that have a high buffering capacity. In these 
terrains, the acid concentrations of the occasional acidic mine effluents are 
usually quite low and are easily accommodated by the naturally alkaline waters. 
In contrast, geologic terrains deficient of calcareous material contain 
streams having low ionic strengths and minimal amounts of alkalinity. In 
these areas, the acid levels of the more prevalent acidic mine drainages tend 
to be much higher than those previously discussed and readily degrade the 
local mildly buffered aquatic systems (_3-_4).-^ 

Factors Affecting Acidity (Sulfur as Iron Disulfide) 

The sulfur content of the overburden may be composed of organic sulfur, 
pyritic sulfur, or sulfate sulfur. Of these three, pyritic sulfur (as mar- 
casite or pyrite) is the most common acid-producing material occurring in 
unweathered strata. In our past studies, which were directed toward an under- 
standing of acid-producing reactions, samples of various rock types were 
placed under simulated weathering conditions and leached with distilled water. 
The leachates derived from the different samples were analyzed, and the degree 
of acidity produced by each sample was measured. Representative splits of the 
rock samples used in the leaching chambers were analyzed for sulfur contents 
and neutralization potentials. A second split of each sample was cast into a 
plastic pellet, polished, and examined by reflected-light microscopy. 

In general, we found that high-sulfur samples produced greater levels of 
acidity than their low-sulfur counterparts. However, in some cases we showed 
that the pyrite morphology was significantly different between the samples 
that produced acid and those that did not, even though the total sulfur con- 
tents (and pyrite sulfur percentages) of the samples were similar. The micro- 
scopic examination of the various samples showed that the pyrite may occur in 
a variety of forms ranging from coarse-grained plant-replacement particles to 
fine-grained framboidal pyrite. In turn, the different pyrite morphologies 
were related to the weathering trends. Of the different types of pyrite noted 
to occur, we found that the framboidal pyrite was the most reactive, being 
inherently less stable than the other, more massive forms ( J_) . This 
relationship is valid when comparing pyritiferous strata that are totally 



^Underlined numbers in parentheses refer to items in the list of references at 
the end of this paper. 



deficient in calcareous material or when comparing the intrinsic oxidation 
potentials of one pyrite type versus another. 

The chemical reactions explaining the oxidation of pyrite and the produc- 
tion of acidity are given (_8) by the following reactions: 

FeSo + 7/2 Oo + HO = Fe'^ + 2S0= + 2H+ (1) 

4 

Fe++ + I/4O2 + H+ = Fe++ + I/2H2O (2) 

Fe"^ + 3H2 = Fe (0H)3(g) + 3H+ (3) 

FeS2(s) + 14Fe+++ + 8H2O = ISFe"^ + 2S0= + 16H+ (4) 

On the surface of a weathered coal mine face, yellow and white crusts may 
occur along the oxidized pyrite horizons within the strata. These highly sol- 
uble salts are the crystallized products of equation 1. 

The ferrous ion generated in the reaction described in equation 1 can be 
further oxidized to the ferric state (in accord with equation 3) to produce 
additional acidity. The ferrous and ferric hydroxides associated with the 
chemical reaction in equation 3 impart the red and yellow-orange color that is 
characteristic of acid mine drainage. The precipitated iron hydroxide is the 
"yellow boy" that is commonly observed in streams and coal mine areas ( 10) . 

Once the oxidation products are in solution, the rate-determining step 
for the acid reaction is the oxidation of ferrous (Fe^) to ferric (Fe ' ' ' ) 
iron (_9 ) . The oxidation of pyrite to hydrous iron sulfates, however, is lim- 
ited by the accumulation of the weathering products. For all intents and pur- 
poses, the soluble pyrite-oxidation products are readily removed from the 
reaction sites by water, consequently, in the absence of alkalinity, the acid- 
producing reactions can proceed unimpeded for indefinite periods of time (_6-7^) . 

Factors Affecting Alkalinity (Calcareous Material) 

Caruccio (_l^-_4) has shown that the quality of mine drainage is also depen- 
dent upon the chemistry of the ground water before mining takes place and the 
calcareous content of the strata (which has the capability of producing an 
alkaline, highly buffered and neutralizing drainage). However, the level of 
alkalinity that can be potentially produced by calcareous material is limited 
by the solubility of the calcareous mineral. Unlike the acid-producing com- 
pounds (the oxidation products of the disulfides), which are extremely soluble 
in water, Geidel (_6-_7) has shown that the dissolution of calcareous material 
in water is fixed by the amount of carbon dioxide present, the time of rock- 
water contact, and the solubility constant of the specified mineral. Once 
equilibrium conditions between the calcareous rock and water are achieved, 
further contact of the water with the alkaline-producing rock does not produce 
additional alkalinity (6-7). 



In some cases, however, shales with a high ion-exchange capacity can 
effect a shift in the equilibriun, thereby causing increased levels of alkalin- 
ity. This chemical mechanism takes place through the absorption of calcium 
and magnesium cations onto the clays of the shales, which effectively shifts 
the carbonate equilibrium reaction to permit greater dissolution of the car- 
bonate mineral with attendant increases in alkalinity. In the absence of 
this mechanism, alkalinity levels will seldom exceed approximately 50 mg/1 
(as CaCOj) under the partial pressure of carbon dioxide (PCO2) found in the 
atmosphere. Substantial increases in pC02 associated with a mature soil and 
vegetative cover would effectively increase the available alkalinity by a fac- 
tor of eight. At best, under equilibrium conditions, the maximum amount of 
alkalinity that can be generated by calcareous material is around 400 mg/1 
(as CaCo3), irrespective of the total amount of calcareous material present in 
the section. 

Blending of acid and alkaline material will initially increase the levels 
of alkalinity since the solubility of calcium -magnesium carbonate is greater 
in an acid solution. However, with time the iron, which is in solution under 
acid conditions, will precipitate at the neutralizing sites and armor the cal- 
careous material against further reactions. In this event, the alkalinity- 
producing material becomes isolated from the aqueous system and the alkaline 
potential of that stratum is lost. For this reason, we oppose blending of 
acid and alkaline overburden materials in backfilling operations and strongly 
advocate the burial of acid material beneath alkaline sequences. 

Calcareous Material-Pyrite Interactions 

Our recent studies, dealing with the chemical weathering properties of 
various rock types, have shown that calcareous material (excluding siderite) , 
in addition to producing alkalinity, strongly affects the rock's weathering 
behavior and plays an important role in controlling the oxidation rate of 
pyrite. Under some circumstances, acidic leachates may dissolve away the pro- 
tective carbonate coating and cause the pyrites to become oxidized. Mildly 
acidic rain, humic acids, or internally produced acid mine drainages, in the 
absence of calcareous material, have the capability of stripping the protec- 
tive carbonate layer from the sulfide site and thus affect the oxidation 
rates. However, with all other things being equal, the greater the calcareous 
material-pyrite ratio is for a sample, the less likely is the sample to pro- 
duce acidity. This relationship, coupled with the results of many leaching 
experiments and whole-rock analyses, has enabled us to develop a relationship 
that can be used to accurately characterize a rock's chemical-weathering 
attribute. This is not to be confused with the now widely used "Smith tech- 
nique," which simply balances the neutralization potential against the pyrite 
content to generate an acid-base account (11-12). For reasons presented above, 
in terms of the different reaction kinetics for pyrite and calcareous material. 
Smith's acid-base account, which ignores the kinetics of acid and alkaline 
release, does not give an accurate assessment of a rock's capability to pro- 
duce acidity or alkalinity. The relationship that we have developed relates 
the empirically derived acid or alkaline production potentials of the differ- 
ent rock types to their varying calcareous-pyrite compositions. We have found 
that the presence of calcareous material (on the order of a few percentages) 



is sufficient to suppress the oxidation of any pyrite present. In these situ- 
ations, samples with pyritic sulfur contents as high as 4 percent were found 
to produce nonacid leachates. This relationship, coupled with the knowledge 
of the geologic distributions of calcareous material and pyrite, plays an 
important role in the design of a sample array that will be used to evaluate 
the nature of the overburden and its potential to produce acid mine drainage. 

Sampling Considerations 

The evaluation of a rock's chemical-weathering attribute and its poten- 
tial to produce either an acid or alkaline leachate is based primarily upon 
the analytical determination of the sample's calcareous material and pyrite 
content. The degree to which the whole-rock analyses of the samples collected 
accurately reflect the actual occurrence of these two components within the 
overburden depends upon the density and spacing of the sampling points as well 
as the distribution of the components within the natural system. If a compo- 
nent is ubiquitous, only one sample is needed for the component to be ade- 
quately sampled. On the other hand, components Vizith highly variable spatial 
orientations require many more samples to adequately define the distribution 
of the component and the character of the system. As discussed above, these 
considerations, coupled with the field-observed distribution patterns of cal- 
careous material and pyrite, permit some generalizations to be made which can 
be used to enhance overburden sampling. 

THE GEOLOGIC DISTRIBUTIONS OF CALCAREOUS MATERIAL AND PYRITE 
AND THEIR RELATIONSHIP TO SAMPLING 

Calcareous Material 



Many of the sedimentary paleoenvironments that were conducive to the for- 
mation and accumulation of calcareous material within the sedimentary column 
are known to have covered large geographic areas. The deposition of the 
calcareous material, unlike that of the clastic sediments which tend to accu- 
mulate near source, generates pervasive blankets of carbonate which are uni- 
formly precipitated over large areas (fig. 1). This is consistent with the 
observed distributions of limestones and rocks with calcareous cement. Many 
stratigraphic studies have paleoenvironmental reconstructions of the Carbonif- 
ferous rocks show that the calcareous facies tend to persist over great dis- 
tances (5). Accordingly, it would be reasonable to expect a calcareous 
horizon to be laterally continuous throughout the overburden of a proposed 
mine site when the geology of a relatively small area of the mine is consid- 
dered within the context of the regional geologic setting. As a result, and 
because of the rather ubiquitous occurrence of calcareous material (in a 
lateral dimension), coupled with the findings of our studies that showed small 
percentages of this material to have an overriding effect on the leachate 
quality of a rock (irrespective, to some degree, of the pyrite content), few 
samples or cores of the overburden would be necessary to adequately assess the 
distribution of potentially alkaline or nonacid horizons in the stratigraphic 
section. 




SOURCE -* 



GRAVEL 






SAND 



^^kD-:v- CLAY 



CALCAREOUS " PRECIPITATE 



{ ' i" ' ■ ■ I 



S A N DST NE '''<^^^-^^^^^^^ ^^■j:^r^^^:X^^^ ,..-.^.^ 



r— < — ', ^ ' — j_^ 

SHALE LIMEY SHALE LIMESTONE 

FIGURE 1. - Idealized representation of sedimentary depositional environments. 

Pyrlte 

Compared with the depositional environments of calcareous material, the 
depositional sites for pyrlte tend to be much more localized. For pyrlte to 
form, a unique set of circumstances combining the availability of sulfate, 
iron, and reducing conditions must be present, and unlike the calcareous 
materials, which generally precipitate from the water column and form blanket 
deposits, the iron sulfide deposits tend to appear as separate clusters or 
widely scattered pockets of accumulation (fig. 2). Within coal seams in 
Pennslyvania and Kentucky the pyritic sulfur content, as represented by total 
sulfur content, was observed to vary by as much as 4 percent (of the total 
weight) over a 1-inch distance (fig. 3). Although not as dramatic, sulfur 
contents were also noted to vary in a vertical dimension (fig. 4). Obviously, 
in these situations, the number and density of samples required to adequately 
document the natural distribution of pyrlte would be much greater than the 
number of samples needed to identify the presence of calcareous material. 




•est 



Fe 



-♦•+ 



^i 



^ (Eh-) 2 -^ 

MICROBIAL ACTIVITY 




FIGURE 2. - Representation of depositional environment of iron disulfide. 



PR7K/2-W 



PR7K/2 



PR7K/2-E 



T3W 



M3W- 



L3W 



o 






2 
%S 



TZcm- 



1 
T2 



1 

L2 



2 

%s 



TsEn 
M3EH 



L3E 





/ 



/ 



2 4 

%s 



FIGURE 3. - Distribution of sulfur contents of Princess Seven cool seam (sample PR7K/2) 
third column samples collected one inch apart; Kentucky. 





PR5K/7(1) 


PR5K/7(2) 


PR5K/7(3) 


PR5K/7(4) 


PR5K/7(5) 


AVG S% = 4.75 


AVG 


s%-- 


= 4.43 


AVG 


S% = 4.99 


AVGS'^o= 5.17 


AVG S% = 3.15 


1 
14-1 


.o 






1 











o 


tI- 






\ 
\ 








6 
1 


^0 


1 

p 


ll- 


X, 




1 
1 



/ 






1 



1 

1 





\ 


ll- 


©"" 











o 


N 


b 




1 1 1 
2 4 6 


I 
2 


1 
4 


1 
6 


1 
2 


1 1 
4 6 


1 1 1 
2 4 6 


1 1 1 

2 4 6 




S% 




S% 






S% 


s% 


s% 



AVERAGE OF 5 LOCALITIES = 4.50% 
CHANNEL SAMPLE =4.05% 

FIGURE 4. - Total sulfur contents of quarter column samples collected from Princess Five coal 
seam (sample PR5K/7); Kentucky. Each location approximately 50 feet apart. 

Interaction of Acid and Alkaline Components 
and Effects on Sampling 

Thus far, it has been shown that the calcareous material tends, by Its 
nature, to occur as pervasive deposits and, If calcareous strata are present, 
will probably underlie an entire mine site. On the other hand, pyrlte depos- 
its are not laterally continuous, the concentrations vary significantly over 
small distances, and the sulfides tend to occur as highly localized deposits. 
Consequently, for a given number of cores of the overburden or samples of the 
hlghwall, the probability of adequately defining the nature and distribution 
of the calcareous material will be greater than for the pyrlte. However, 
these expected differences can be minimized because of the effect that calcar- 
eous material has upon the oxidation rate of pyrlte. Because minor amounts 



10 



of calcareous material mollify the pyrite oxidation reactions, the presence of 
calcareous material in a particular horizon becomes the most important factor; 
accordingly, large variations in pyrite content can be tolerated within the 
sample array. As an illustration, a pyritiferous zone having around 2 perecnt 
sulfur, the pyrite may be intercepted by some cores and because of the natu- 
rally variable lateral distribution may not be detected in samples from adja- 
cent cores. If the same high-sulfur horizon is shown to have significant 
concentrations of calcareous material, then the lateral variation of the 
pyrite and the inadequacy of sampling can be partially ignored because the 
probability is that these samples will produce nonacid leachates. For those 
stratigraphic horizons where calcareous material is present, the number of 
samples required to adequately assess the occurrence of nontoxic strata is 
relatively small. On the other hand, the lack of calcareous material in a few 
holes or channel sample strongly points to the probable absence of alkaline- 
producing strata in the overburden and underscores the need to increase the 
number of samples. In this case a higher core hole spacing is necessary in 
order to adequately identify the distribution of pyrite and the potential of 
that horizon to produce acidity. 

In the former example, a statement can be made with a reasonable degree 
of confidence that the probability that the strata will produce acid is low. 
In the latter example, however, a positive judgment cannot be made if pyrite 
is not found in the sample. The absence of pyrite does not necessarily indi- 
cate improbability that the strata will produce acid. Localized pyrite depos- 
its may in fact be present but be missed by an inadequate sampling network or 
insufficient number of samples. 

CONCLUSIONS AND INTERPRETATIONS OF DATA 

The array presented in tables 1 and 2 is a synthesis of the various con- 
cepts discussed above and integrates (1) the chemical nature of acid mine 
drainage, (2) the kinetics of acid formation and alkalinity production, (3) 
the interaction of calcareous material and pyrite, and (4) the geologic dis- 
tribution of the responsible alkaline and acid mineral components into a sum- 
mary form. For such reasons as economic considerations, thickness of the 
overburden, size of the mine or area that will be disturbed, objectives of the 
sampling program, accessibility of the area, contractural time constraints, 
and the frequency of sampling, the density and number of samples required to 
adequately define the natural system cannot be quantitatively postulated. 
Because of the unique set of circumstances that exists at each mine and the 
need for site-specific information to accurately evaluate each site, the fol- 
lowing conclusions can only be applied and discussed in general relative terms. 

The matrix shown in table 1 outlines the probable leachate quality that 
would be expected from samples having a variety of calcareous-pyrite ratios. 
These conclusions are based on the results of our recent studies and because 
none of the samples used in the study had sulfur contents greater than 3 per- 
cent, the matrix is constrained by this value. The frequency of sampling 
reflects the geologic distribution of calcareous material and pyrite. The 



11 



degree of confidence (table 2) that could be expected, in terms of an assess- 
ment of a sample's capability to prodtice nonacid, alkaline, or acid leachate, 
combines the laboratory-derived rock-weathering expectations and the field- 
observed distributions of pyrite and calcareous material into an array that 
outlines the leachate quality that may be anticipated and the necessity of 
procurring additional data. 

TABLE 1 . - Matrix showing anticipated rock weathering reaction 
for a variety of calcareous-pyrite ratios (CPP) 



Pyrite 


Calcareous 


Calcareous 


content 


material 


material 




absent 


present 


Less than 


Neutral, generally 


Alkaline, high-ionic- 


0.5 percent. 


low-ionic strength 
leachate. 


strength leachate. 


Greater than 


Acid, high ionic 


Nonacid, high ionic 


0.5 percent 


strength with 


strength, low to 


but less than 


sulfate and 


moderate sulfate. 


3 percent. 


iron. 


low iron. 


Frequency of 


Number of samples 


Number of samples 


sampling. 


must be maximized. 


can be minimized. 



TABLE 2. - Degree of confidence^ 



Component 


Expected 
nonacid 


Expected 
alkaline 


Expected 
acid 


Need more 
data 


Calcareous material.. 
Pyrite (less than 
3 percent ) 


+ 
+ 


+ 


+ 









•'■Analysis of sample shows presence (+) or absence (-) of 
component. 



The matrix presented in table 1 may be used as a guide to determine the 
number of samples that must be collected or the density of core hole spacing 
needed to adequately sample a geologic terrain for acid production potential. 
These conclusions are based upon the fact that calcareous-enriched strata tend 
to occur as laterally pervasive blanket deposits, whereas pyrite has been 
noted to occur as highly localized pockets. The geologic distributions of cal- 
careous material and pyrite in the Appalachian bituminous coalfield are known 
to have these patterns, and accordingly the matrix presented above could be 
useful to personnel concerned with overburden sampling and the identification 
of potentially acid-producing material in the region. 



12 



REFERENCES 

1. Caruccio, F. T. , J. Ferm, J. Horne, G, Geidel, and B. Baganz. Paleoenvi- 

ronment of Coal and Its Relation to Drainage Quality. U.S. EPA (Cin- 
cinnati, Ohio), EPA-600/7-77-067, June 1977, 107 pp. 

2. Caruccio, F. T., and G. Geidel, Geochemlcal Factors Affecting Coal Mine 

Drainage Quality. Ch. in Reclamation of Drastically Disturbed Lands, 
ed. by F, W. Schaller and P. Sutton. American Society of Argonomy., 
Madison, Wis., 1978, pp. 129-148. 

3. Caruccio, F. T,, and R. Parlzek. An Evaluation of Factors Affecting Acid 

Mine Drainage Production and the Ground Water Interactions in Selected 
Areas of Western Pennsylvania. Proc. 2d Symp. on Coal Mine Drainage 
Res., Pittsburgh, Pa., May 14-15, 1968. Bituminous Coal Research, 
Monroeville, Pa., 1968, pp. 107-151. 

4. . Characterization of Coal Mine Drainage. Ch. in The Ecology of 

Resource Degradation and Renewal, ed. by M, J. Chadwlck and G. T. Good- 
man. Blackwell Scientific Publications, Halstead Press, New York, 1975, 
pp. 197-203. 

5. Ferm, J., and J. Horne. Carboniferous Deposltional Environments in the 

Appalachian Region. Carolina Coal Group, Dept. of Geology, University 
of South Carolina, Columbia, S.C, 1979, 760 pp. 

6. Geidel, G. Alkaline and Acid Production Potentials of Overburden Mate- 

rial: The Rate of Release. Reclamation Review, v. 3, No. 1, 1980, 
pp. 1-7. 

7. Geidel, G. , and F, Caruccio, Time as a Factor in Acid Mine Drainage Pol- 

lution. Proc. 7th S3mip. Coal Mine Drainage Res., Louisville, Ky. , 
Oct. 18-20, 1977., Bituminous Coal Research, Monroeville, Pa., 1977, 
pp. 41-50. 

8. Singer, P,, and W, Stumm, Kinetics of the Oxidation of Ferrous Iron. 

Proc. 2d Sirmp. Coal Mine Drainage Res., Pittsburgh, Pa., May 14-15, 
1968. Bituminous Coal Research, Monroeville, Pa., 1968, pp. 12-34. 

9. . Acidic Mine Drainage: The Rate Determining Step. Science, 

V, 167, Feb, 20, 1970, pp. 1121-1123. 

10. Smith, E., and K. Schumate. Sulfide to Sulfate Reaction Mechanism. U.S. 

EPA, Water Pollution Control Res. Series, 14010-F.P.S.02/70, 1970. 

11. Smith, R., W. Grube, T. Arkle, and A. Sobek. Mine Spoil Potentials for 

Soil and Water Quality. U.S. EPA (Cincinnati, Ohio), EPA-670/2-74-070, 
1974, 303 pp. 

12. Sobek, A,, W, Schuller, J. Freeman, and R. Smith. Field and Laboratory 

Methods Applicable to Overburden and Mlnesolls. U.S. EPA (Cincinnati, 
Ohio), EPA-600/2-78-054, March 1978, 204 pp. 



13 



OVERBURDEN SAMPLING AND ANALYSIS' 



by 
Richard M, Smith^ and John C. Sencindlver-' 



ABSTRACT 

Research at West Virginia University has demonstrated that overburden 
characterization techniques can be useful in mining and reclamation practices 
if they are consistently applied. The concept of surface raining provinces in 
West Virginia has also provided practical guidelines for decisions about sam- 
pling, analysis, and interpretations. On specific overburden columns proper- 
ties of color, texture, presence of carbonates, hardness, bedding, and degree 
of fracturing or disintegration can be used to separate sampling units. 

When a complete highwall exposure or exploration core is available, the 
best approach to sampling is to begin with the deepest coal seam to be mined. 
The first samples should be taken immediately above and below the coal seam. 
These samples commonly represent the maximum sulfur percentage in the overbur- 
den. Next, the entire column should be examined, and each different rock unit 
between the coal and the soil profile should be sampled. Three samples should 
generally be taken from soil profiles: One from the darkened uppermost layers; 
one from the central part of the subsoil where plant roots are common; and one 
from the material above the bedrock where roots are sparse or absent. 

INTRODUCTION 

In the interest of mining coal economically and in an environmentally 
sound manner, it is important to concentrate on overburden properties that 
influence mining methods, reclamation, plant growth, and soil and water 
quality. Techniques that allow soil and rock properties to be sampled con- 
sistently are more important than single-parameter determinations based on 
geological, pedological, or ecological considerations. 

During the past few years, simplified schemes of soil and rock sampling 
and quick testing have evolved that can be followed and applied by people with 
varied backgrounds. Routine laboratory processing as well as adapted chemical 
and physical measurements have been described in step-by-step procedures 
designed to meet common needs for overburden characterization and definition 
of manageable units of manmade soils (5).^ Use of these interdisciplinary 

^Published with the approval of the Director of the West Virginia Agricultural 
and Forestry Experiment Station as Scientific Paper No. 1645. 

^Professor. 

■^Assistant professor. 

Both authors are with the Division of Plant and Soil Sciences, College of 
Agriculture and Forestry, West Virginia University, Morgantown, W. Va. 

'^Underlined numbers in parentheses refer to items in the list of references at 
the end of this paper. 



14 



overburden characterization techniques offers the potential for saving money, 
increasing coal production, and simplifying regulations, 

SOIL AND GEOLOGIC MAPS 

A modern detailed soil survey will be a valuable aid to persons planning 
a major land disturbance such as a surface mine. However, such a survey will 
lack sufficient detail for some purposes. Although geologic information can 
be inferred from the soils, the soil survey only gives certain information 
about the top several feet of earth material. 

Geologic maps will give information concerning the coal seams and the 
major rock strata of a particular area. Although these maps, like the soil 
survey maps, aid general planning, the details of rock properties cannot be 
shown. Therefore, since rock strata are known to vary both vertically and 
horizontally, the overburdens need to be sampled and analyzed for details of 
property variation, 

SAMPLING OVERBURDEN COLUMNS 

The best approach to complete overburden sampling below the soil is to 
begin with the coal that is to be mined. This assumes that an exploration 
core or a complete highwall exposure is available. In either case, a sample 
should be taken representing 12 inches (30 cm) of material immediately above 
the coal, and another sample should be taken representing 12 inches (30 cm) 
or less immediately below the coal. These samples often, but not always, 
represent maximum sulfur percentages in the overburden column. 

Next, the entire column should be examined in terms of observable rock or 
earth properties from 1 foot (30 cm) above the coal to the bottom of the soil 
profile as defined later. This examination will result in separation of the 
column into kinds of material based on properties. Any layer thinner than 
5 inches (12 cm) should ordinarily be considered as transitional between adja- 
cent thicker strata, unless the thin unit affords contrasting properties of 
special interest such as a limestone or carbolith, in which case it should be 
sampled separately. 

The rock units recognized for sampling will differ in color, texture, 
hardness, bedding, and degree of fracturing or disintegration. Colors are 
observable in place but should be checked with Munsell color chips after grind- 
ing dry samples to pass a 60-mesh screen. Texture is estimated by eye and 
feel. Individual sand grains can be seen with little or no magnification and 
feel gritty in a wet sample. Silt, on the other hand, feels smooth, and clay 
feels sticky when material is thoroughly worked as a paste. The textural 
class called loam means that sand, silt, and clay are all represented with no 
single particle size dominant, Mudrocks often have loam textures, but they 
may also be dominantly silty or clayey. If sand is dominant, it may help to 
indicate whether the grains are fine (barely visible), medium (easily visible), 
or coarse (almost pebbles and often containing some pebbles). Hardness of 
fine-textured rock is checked with fingernail (hardness 2,5), penny (hardness 
3,0), and knife (hardness 5,5), as well as by other common hardness standards 



15 



c 

O 

NI 

T3 
<U 
U 
<D 

x: 
-p 



o 
en 



(1) Horizon 1 



(2) Horizon 2 



(3) Horizon 3 



(4) 



(5) 



(6) 



(7) Roof (30 cm) 



Coal 



(8) Undersoil (30 cm) 



(9) 



(10) Carbolith 



(11) 



(12) Roof (30 cm) 



Coal 



(13) Undersoil (30 cm) 



Darkened Surface 



Bottom of significant roots 

Highly weathered rock, colluvium, 
till, etc. 

Maximum depth 150 cm 



Carbonates increase if present 
(pH increase) 



Chroma Change 



Scheduled for mining 



Scheduled for mining 



FIGURE 1. - Sampling diagram. The numbers in parentheses indicate the overburden samples 
that would be taken for laboratory analysis. 



16 



if needed. The presence of carbonates is determined with 10 percent hydro- 
chloric acid applied to field samples and checked more accurately in the 
laboratory on dry powders. 

Once the major rock units have been established, appropriate samples are 
taken from each. With relatively uniform sandstone rock types, at least one 
sample is taken to represent each 5 feet (150 cm) of thickness. With other 
rock types, as well as loess (silt), glacial drift, and colluvium, one sample 
is taken for each 3 feet of thickness or less. 

Sampling as outlined is simple. It requires no great theoretical 
competence in geology or pedology. It is aimed at ascertaining practical 
properties. Such sampling averages about one sample per 3 feet (90 cm). The 
scheme is summarized in figure 1, 

If a person lacks confidence in sampling, he or she initially mark the 
entire core at 1-foot intervals and take a 5-inch (12.5-cm) section from near 
the center of each foot. If, after this arbitrary method has been followed, 
certain successive samples appear similar, it would be satisfactory to combine 
them, saving only part of each original sample, Blasthole drillings offer a 
speedy and easy method of collecting overburden samples. The rock chips 
expelled from the hole are caught at 1-foot intervals. Successive samples may 
be combined after rock units have been determined. 

In referring to overburden it should be understood that the soil profile 
is included as well as rock or soil under the coal. Also, "rock unit" refers 
to any layer in the overburden that differs in properties that may influence 
the handling of the material or the quality of resulting minesoil or water, 
regardless of whether these layers are considered to be different geologic 
strata. 

SOIL PROFILES 

Soil sampling in the top 5 feet (150 cm) usually requires three samples: 
One from the uppermost layers, darkened by organic matter; one from the cen- 
tral part of the subsoil where plant roots are common; and one from the soil 
material above bedrock where roots are sparse or absent. In the Appalachian 
region, bedrock may occur at a shallow depth, in which case only two soil sam- 
ples may be needed. If bedrock starts are deeper than 150 cm, the third soil 
profile sample should stop at the 150-cm depth. Special cases may require 
four or five soil profile samples. The assistance of a soil scientist may be 
needed in these special cases, such as soil profiles with prominent fragipans 
(brittle subsoil horizons with high bulk density) or with slowly permeable 
clayey subsoils. These horizons will show distinctive mottling (or variation) 
of colors, part of which are gray or sometimes almost white. That is, brown, 
yellow, and red colors will be mixed with or mottled with gray (low-chroma) 
materials, in definite horizons of the soil profile, indicating that the color 
mottling formed in place by soil development processes. Such mottling should 
not be confused with color variations resulting from differences in rock 
properties and rock weathering. 



17 



Fragipans and slowly permeable clayey horizons in soil profiles are 
invariably unfavorable for surface or near-surface placement after mining. 
When blended with a high proportion of mixed rock materials, these mottled 
soil layers are not likely to be especially harmful, but they should be 
rejected for placement near the surface. 

Fragipans in West Virginia are usually strongly acid, infertile, hard 
when dry, and largely impenetrable by roots except along certain vertical 
planes between coarse blocks or prisms. Mottled clayey horizons may be more 
variable in chemical properties but are typically physically unfavorable 
because of too much fine clay and resulting poor structure. 

To summarize, in sampling soil profiles, three samples from each soil 
profile are usually sufficient for chemical testing. However, mottled subsoil 
horizons should be noted if present and should be mixed into the fill rather 
than concentrated anywhere in the plant root zone or in positions where they 
may encourage seepage or slips on outslopes, 

LOCATION OF OVERBURDEN COLUMNS 

We have stated elsewhere (4) from varied experiences with overburden 
observations, sampling, and analysis, that an analyzed column within 1 km 
(0,6 mile) of an operation will usually prove helpful if studied and used by 
people involved in mining coal. Regardless of distance to an analyzed column, 
it is essential that operators pay close attention to overburden changes as 
mining progresses. Important changes may occur either gradually or abruptly, 
in either case are not likely to escape notice by an observant person. It is 
the responsibility of such people to be alert to rock changes that may call 
for additional selected sampling or adaptation of procedures and treatments of 
new conditions. In practice with distances less than 1 km from an analyzed 
column, the chance of rock or soil changes that require major alterations in 
mining is slight, especially when operators are alert and are willing to build 
in some margin or safety against toxicity or other overburden-related 
problems. 

One aid to West Virginia overburden work that has become a part of our 
approach is the concept of there being three surface mining provinces in the 
State and southward. Boundaries of these provinces are necessarily highly 
generalized, as expected on a small map of a large geographic area, and obvi- 
ous inclusions occur within each province. At the same time, the province 
concepts tend to provide useful guidelines for decisions about sampling and 
interpretations without compromising the basic principle that measurable geo- 
graphic and soil properties must be granted precedence over intangibles based 
on age or theories of genesis. 

The surface mining provinces are defined by Arkle (_2) are shown in fig- 
ure 2, The original definitions were based on stratigraphy, structure, physi- 
ography, and culture. As research expanded, the surface mining provinces 
became more strongly based on overburden properties (J_) . Thus, province 1 is 
broadly defined as having overburden rocks tl^jxt are low in total sulfur, low 
in bases, and resistant to weathering. The overburdens of province 2 have a 




\^il:>^ Horizon of the Pittsburgh Coal 

Base of the Pennsylvanian System 
Limit of minoble coal in Province 3 



Direction of IhicKening 
of bosins of deposition 




/ 




»• Surface mining provinces 



FIGURE 2. - Surface mining provinces in West Virginia. 

wide range of rocks that are high in total sulfur and low in bases. Prov- 
ince 3 is broadly defined as having overburden rocks that are high in total 
sulfur, high in bases, and dominated by mudstone, shale, and limestone. 

INTERPRETING LABORATORY MEASUREMENTS 

Methods for overburden characterization have been investigated at West 
Virginia University and are given in detail in a previous publication (5), To 
use such techniques effectively, it is necessary that analyses be done selec- 
tively. Rarely is a problem solved simply by ordering determination of essen- 
tially everything that we know how to measure. This approach commonly buries 
and hides what we really want to know or introduces errors that invalidate 
apparent relationships. 

Extreme care is necessary to insure that final results provide a true 
picture of the field situation that is under consideration. If some inter- 
mediate step of sampling, processing, extraction, or analysis is false, the 



19 



results may be completely misleading. This is the reason that our approach 
to overburden characterization includes built-in checks and balances such as 
definitely defined rock types and soil horizons, fizz tests for carbonates, 
hardness tests by rock and mineral types, and taste, smell, and finger-sense 
tests. If laboratory analyses are selected carefully to answer well-defined 
questions and the quality control of laboratory tests is repeatedly checked 
and maintained, the results from overburden sampling followed by laboratory 
analyses and interpretations can be extremely helpful to successful mining, 
land improvement, and favored land use. Whenever such sampling, analyses, and 
interpretations are completed, certain reasonable predictions can be made 
without the overburden studies. 

Most interpretations of acid versus basic properties of coal overburdens 
in West Virginia have involved personal judgment, not only about the overbur- 
den properties but also about the mining operators themselves, and the quality 
of regulatory control. Obviously, even excellent recommendations succeed only 
if carried out. 

One of the first attempts to quantify acid-base accounting recommenda- 
tions in West Virginia was by Hoffman (3). More recntly, this approach has 
been emphasized by the Surface Mine Drainage Task Force (6) and in ongoing 
research at West Virginia University (7). It is anticipated that additional 
cooperative studies with mining operators and regulatory agents will reinforce 
standardized interpretations now being used or will indicate where revisions 
are needed. This kind of cooperative effort constitutes the ultimate 
real-world test of validity of methods and interpretations. 



20 



REFERENCES 

1. Aramons, J. T. Minesoll Properties, Root Growth and Land Use Implications. 

Ph.D. Dissertation, W. Va. Univ., Morgantown, W. Va,, 1979, 221 pp. 

2. Arkle, T, Mine Spoil Potentials for Water Quality and Controlled Erosion, 

U.S. EPA, 14010 EJE 12/71, 1971, 206 pp; available from National Tech- 
nical Information Service, Springfield, Va., PB 208 347. 

3. Hoffman, J. W. Unpublished report on DLM Corporation. Distributed at 

Cooperative Symp. on Surface Mining sponsored by the U.S. EPA, Zanes- 
ville, Ohio, July 19-20, 1977; available through Ohio Department of 
National Resources, Columbus, Ohio. 

4. Smith, R. M. , A. A. Sobek, T. Arkle, Jr., J, C, Sencindiver, and J. R. 

Freeman. Extensive Overburden Potentials for Soil and Water Quality. 
U.S. EPA-600/ 2-76-184, 1976, 310 pp; available from National Technical 
Information Service, Springfield, Va., PB 257 739/AS. 

5. Sobek, A. A., W. A. Schuller, J. R. Freeman, and R. M. Smith. Field and 

Laboratory Methods Applicable to Overburdens and minesoils. U.S. EPA 
(Cincinnati, Ohio), EPA-600/ 2-78-054, 1978, 204 pp. 

6. Surface Mine Drainage Task Force. Suggested Guidelines for Method of 

Operations in Surface Mining of Areas with Potentially Acid-Producing 
Materials. Green Lands, v. 9, No. 2, 1979, 20 pp. 

7. Tettenburn, Frank M. Overburden Characterization and Its Role in Premine 

Planning of Two West Virginia Surface Mines. M.S. Thesis, W, Va, Univ., 
Morgantown, W. Va., 1980, 164 pp. 



21 



USE OF SOIL-OVERBURDEN DATA IN MINE 
PLANNING AND DEVELOPMENT 

by 

Vance P. Wiram^ and David S, Ralston^ 



ABSTRACT 

The Surface Mining Control and Reclamation Act of 1977 mandates detailed 
characterization of soil, geologic, and hydrologic resources for mine planning 
and environmental assessment of coal mine development. This paper describes 
efforts taken by AMAX Coal Co. to gather and utilize pertinent resource data 
throughout the permitting, mine planning, and actual mining and reclamation 
processes. Methodology of sampling and analytic characterization of the soil- 
overburden resources are defined. Details of data input into mine planning 
are outlined. Emphasis is placed on communications and tracking (follow- 
through) of mining and reclamation objectives throughout development of the 
coal reserve. Key regulatory issues and research needs relative to evaluation 
of soil-overburden resources are discussed, 

INTRODUCTION 

In the late sixties and early seventies, surface mine reclamation essen- 
tially consisted of grading to an acceptable landscape and establishing an 
adequate vegetative cover. Today, the term "reclamation" has taken on a 
broader meaning that practically spans the spectra of the atmosphere, litho- 
sphere, and hydrosphere. The concept of total reclamation is evolving to the 
point where all concerns related to air, soil, and water to be addressed 
before, during, and after mine development. Ironically, because of "sins of 
the past" in which some historic mining efforts have created "lunar landscape 
topography," the coal industry now faces challenges which form a technological 
standpoint may be as great and exciting as the challenges faced in going to 
the moon. 

The "seed" of such a rapid advance in reclamation was sown with the pas- 
sage of the National Environmental Policy Act of 1969, which reflected the 
"environmental movement" of the Nation in the late sixties. Culmination of 
the concept of total reclamation arrived with passage of the Surface Mining 
Control and Reclamation Act of 1977. The act charges the coal industry with 
the dual responsibility to — 

"restore the land affected to a condition capable of supporting the 
uses which it was capable of supporting prior to any mining, or 
higher or better use,,, Sec. 515(b)(2), and minimize the disturb- 
ances to the prevailing hydrologic balance at the minesite and in 

^Manager of Environmental Services, AMAX Coal Co., Indianapolis, Ind. 
^Senior environmentalist (agronomist), AMAX Coal Co., Indianapolis, Ind. 



22 



associated offsite areas and to the quality and quantity of water 
surface and ground water systems .. .See. 515(b)(10)" (13).-^ 

The ramifications of the change are far reaching. 

To meet the challenge of the act, substantial Input from several scien- 
tific disciplines (geology, pedology, agronomy, ecology, etc.) is required. 
The main purpose of this paper is to review the inputs of soils and geology 
into mine planning and development at AMAX Coal Co. The subject will be 
addressed by attempting to answer four basic questions: (1) l^at soil- 
overburden information is collected? (2) How is the information gathered? 

(3) How is the information used in mine planning and actual operations? 

(4) What regulatory issues and research needs exist relative to soil- 
overburden characterization? 

SOIL-OVERBURDEN CHARACTERIZATION 

Since 1974, efforts have been underway to assess all soil-overburden 
materials for both active and prospective mines. Detailed characterization is 
conducted under methodologies defined in the SOAP Program (soil-overburden 
analysis program). The program is dynamic, possessing the flexibility to 
adapt to local needs on a site-specific basis. Regional environmental con- 
cerns and desired reclamation goals have been the key elements around which 
the program has been developed. The program involves soil-overburden 
evaluations before and after mining. 

Premine Evaluations 



Premine assessment involves detailed mapping and sampling of all major 
soil and overburden resources of a given area. The mechanics of sampling are 
accomplished by one of three methods: (1) Soil hand probe or grab sample, 
(2) truck-mounted soil probe, or (3) drill rig with multiple sample retrieval 
methods. All samples are described according to established standards and 
forwarded to our Midwest Area Laboratory in Evansville, Ind., for analyses. 
The following is a brief description of the procedures used in sampling and 
analyzing the various soil-overburden materials. 

Soil characterization of a reserve area begins with a Soil Conservation 
Service (SCS) map and soil profile descriptions of major map units. If an 
area lacks a SCS map suitable for planning purposes, such a map is generated 
by a soil scientist on the SOAP staff. A member of the SOAP staff is a certi- 
fied soil classifier. The map is prepared at SCS mapping standards in close 
cooperation with local SCS personnel. Once completed, the map is reviewed and 
approved prior to official use. Major soil series identified on the soils map 
are sampled at a minimum of two sites. Representative samples of the soil 
horizons are described and collected for analytic purposes. Table 1 defines 
the routine and select analyses completed for all samples. 



^Underlined numbers in parentheses refer to items in the list of references at 
the end of this paper. 



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24 



VThen drilling SOAP holes with the drilling, all soil and geologic mate- 
rials encountered are sampled. Grid spacing selections of a drill program are 
site-specific based solely on the geologic variability of the coal reserve. 
For areas in which the geologic variability is low (lithologically homogene- 
ous), a drilling pattern on 1-mile centers is generally followed. Such grid 
spacing provides ample data to define each major stratigraphic unit for pre- 
mine planning purposes. Such an approach is supported by overburden studies 
completed by Hester and Leung (5) for coal seams of Kentucky, Widespread 
homogeneity of overburden reflects uniform geochemical conditions within the 
depositional environment of the parent sediment, Caruccio (_2) and Home and 
Perm (7) have demonstrated the role of the sedimentary environment of 
deposition in controlling the geochemical properties of the sediment. 

For coal reserves in which overburden conditions reflect high geologic 
variability, a half-mile grid spacing is generally applied. Offsets from the 
drill pattern are sometimes necessary to evaluate glacial and bedrock units of 
elongate geometry (that is, glacial drift deposits in preglacial valleys and 
channel sandstones common to both Pennsylvania and Tertiary coal-bearing 
sediments) , 

Unconsolidated materials are sampled by either the Shelby tube or the 
split-spoon method. If a continuous section of the unconsolidated profile is 
desired, Shelby tubes on 2-foot increments are used for sample retrieval. If 
it is not necessary to obtain a continuous section but a preliminary stabil- 
ity assessment of the unconsolidated materials is desired, samples are taken 
via the split-spoon method. Samples taken by split-spooning are removed from 
the sampling tool, bagged, and properly marked relative to depth taken. Sam- 
ples taken by the Shelby method are sealed, and the tubes are sent to the 
laboratory for extrusion. Regardless of the method used, all materials are 
described and identified by staff geologists as to geologic type (soil, loess, 
glacial drift, alluvium, colluviun, regolith, or combinations thereof, etc). 
Table 1 defines the routine and select analyses performed on the various 
unconsolidated materials. 

Sampling of the bedrock overburden is achieved by obtaining continuous 
strata cores to a depth of 10 feet below the deepest coal seam considered for 
development. All recognizable rock units greater than 5 feet are sampled. 
All units less than 5 feet are considered components of a larger rock body. 
Sampling intervals within respective lithologic units are dependent upon the 
degree of weathering or oxidation state, as indicated by color. 

Weathered bedrock materials are usually sampled on 10-foot intervals. 
The entire 10-foot segment of core is combined and crushed, and a split sam- 
ple is taken to be representative of that particular interval of the rock unit. 
All unoxidized rock units (dark colored) are sampled on 5-foot intervals, A 
split sample of the interval is taken in the same manner described above. 
Table 1 lists the routine and select analyses of the various bedrock materials. 



25 



Postmlne Evaluations 

Once reclamation grading Is complete, efforts are made to characterize 
the cast overburden materials (spoil) left at the graded surface. Samples 
are collected on a quasl-grld system with offset sampling in obvious poten- 
tial problem areas. In the Midwest, grab samples of rock materials, as well 
as samples taken of the upper foot of the spoil surface, are combined and sub- 
mitted for analyses. Attention is focused during descriptive work on a rela- 
tive percent of type geologic materials comprising the representative spoil 
sample. Primary concerns are rock texture and potential acid-forming composi- 
tion. Table 1 defines routine and select analyses completed on spoil samples. 

After topsoil and subsoil (if required) are replaced, the various materi- 
als are sampled for soil amendment (lime and fertilizer) and reclamation docu- 
mentation purposes. In the Midwest, the samples are collected at random. In 
the West, sampling of the final reclaimed land is conducted on a 2-acre grid 
system. Two samples are collected at each site. One sample is representative 
of the replaced topsoil and the other of replaced subsoil. The maximum depth 
sampled is 5 feet. For both the raidwestern and western operations, table 1 
defines the analyses completed in the samples collected. 

DATA USE IN MINE PLANNING 

The act mandates that sufficient soil and overburden be collected to 
properly plan and assess the cumulative impacts of a proposed operation on the 
environment. Table 2 defines sections of the act that specifically require 
the gathering and use of soil-overburden data. The Office of Surface Mining 
permanent program provides a skeletal outline for addressing data input to 
mine planning and development of an operation. 

TABLE 2. -Soil-overburden characterization and Public Law 95-87 



Section 



Coverage 



PERMITTING 



507(b)(14) 
5G7(B)(15) 
508(a)(12) 



Application: Physical aspects. 
Application: Chemical aspects. 
Reclamation plan: Acid and toxic potentials, 



PERFORMANCE STANDARDS 



515(b)(3), 
515(b)(5) 



515(b)(7)(A)&(B), 
515(b)(10)(A)... 



Backfill and grading: Cover of acid forming 

and other toxic materials. 
Topsoil: Substitute and/or supplement 

materials. 
Prime farmlands: Soil resource restoration. 
Hydrologic balance: Minimize contamination. 



Table 3 defines those pertinent sections of regulations that require soil- 
overburden characterization and input. AMAX began data gathering 4 years in 
advance of the act. Actual input into mine planning and operation development 
has been increasing. The following is a brief description of how the data are 
incorporated into mine planning and used during actual coal development. 



26 



TABLE 3. - Soil-overburden characterization and OSM 

permanent program 



Section Coverage 



PERMITTING 



701.5 

779(b)(1) 

779.21(b) 

780.18(b)(5).... 
785.17(b)(3)&(5) 
785.19(d) 



Definitions. 

Geological descriptions. 

Soil resource information. 

Soil testing. 

Prime farmlands. 

Alluvial valley floors. 



PERFORMANCE STANDARDS 



701.5 

816.21(e)(1) 

816.25 

816.48(a)... 
816.103(a).. 



816.152-816.174, 



Definitions. 

Topsoil substitutes and supplements. 
Nutrient and soil amendments. 
Hydrologic balance: Groundwater. 
Backfill and grading: Cover of acid 

and toxic overburden. 
Construction of roads. 



Exploration 

SOAP input occurs from the exploratory stages of mine development through 
final restoration of a mine site. Although financial commitments are often 
limited in exploratory efforts, a quick assessment of soil-overburden 
resources is made. Major emphasis is placed on identifying potential problems 
that could prelude attainment of desired company mining and reclamation objec- 
tives. Following data evaluation, a brief summary of findings and recommenda- 
tions are included in the engineering feasibility study of an exploration 
project. From the information generated, management is better equipped to 
make land option and future investment decisions regarding the property. 

Permitting — Definition of Baseline Conditions 

The soils, geology, and hydrogeologic data collected over the past 
6 years are used to fulfill existing permit application requirements for all 
active and proposed operations. For the most part, information gathered to 
date for a given property has been sufficient for defining environmental base- 
line conditions as outlined in section 779(b) (13) of the permanent program. 

During the baseline-data-gathering process, major emphasis is placed 
on identification of the limiting factors of the various soil and geologic 
materials. Limiting factors of a physical and chemical nature are summa- 
rized in table 4, For purposes of this paper, limiting factors are defined 
as those physical or chemical properties of the overburden that have the 
potential for creating undesirable results in the mining and reclamation 
process. The undesirable results could range from decreased coal production 
to environmental degradation. 



27 



TABLE 4 . - Limiting factors of soil-overburden materials 



Factor 



Comments 



PHYSICAL 



Stability..., 
Bulk density, 



Percent clay con- 
tent and type. 



Rock content, 



Erodibility, 



Governs potential slope failure of highwall; defines con- 
ditions for topsoil and root media handling. 

Affects root development and soil moisture storage; affect 
surface water infiltration and permeability. 

Affects moisture availability; affects aggregation and 
tilth; governs shrink-swell of soil; determines cation 
exchange capacity. 

Dominant factor in determining suitability of graded cast 
overburden for soil replacement; affects moisture 
availability. 

Defines erosion potential of proposed actions. 



CHEMICAL 



Acid forming. 



Alkali forming 
(carbonates) , 



Alkali forming 
(sodic) . 



Salt forming 
(saline) . 

Trace metals. 



Productivity — Acids generated are phytotoxic below pH 4.5. 

Hydrologic regime — Potential for surface and ground water 
quality alterations. 

Productivity — Inhibits plant nutrient uptake and restricts 
moisture availability. 

Hydrologic regime — Potential for surface and ground water 
quality alterations. 

Productivity — Inhibits moisture availability and root pen- 
etration; increases reclaimed land instability and 
causes traversibility problems of fann equipment. 

Hydrologic regime — Increases potential for total suspended 
solids (TSS) problems with surface; increases potential 
for surface and ground water quality alterations. 

Productivity — Phytotoxic to sensitive plants. 

Hydrologic regime — Surface and ground water quality alter- 
ations (i.e., total dissolved solids (TDS). 

Productivity — Potential for development of phytotoxic 
conditions. 

Hydrologic regime — Potential for surface and ground water 
quality alterations . 



Highwall instability can lead to excessive rehandling of overburden mate- 
rials, not to mention the potential for equipment damage. Improperly placed 
acid overburden leads to surface and ground water contamination and possible 
revegetation problems. Such undesirables lead to treatment costs, including 
soil covering, liming, and neutralization treatment of drainage. Such envi- 
ronmentally related problems when continued unchecked can ultimately lead to 
regulatory violations. 



While identification of limiting factors is aggressively pursued, favor- 
able properties of soil-overburden materials are by no means overlooked. A 
constant effort is made to define those materials that have the potential for 
achieving maximum revegetation productivity and hydrologic benefits following 
reclamation. In the case of revegetation, a twofold objective exists. First, 
topsoil and subsoil materials are compared with underlying loess, glacial till. 



28 



and bedrock materials in order to define the most suitable materials for rec- 
lamation purposes. Secondly, for areas in which topsoll cannot be removed 
owing to physical restraints, efforts are made to define alternative (substi- 
tute) materials in the over-burden. The following list serves as a basic 
guide in completing an alternative topsoll request to the regulatory authority; 

Physical decriptlon (type and depth) 

1:1 soil/water pH 

Phosphorus 

Potassium 

Organic matter 

Texture class (percent sand, silt, clay) 

Except for organic matter analyses require laboratory certification: 30 CFR 
816.22(e)(l)(li). 

For steeply sloping land and wet areas where topsoll removal is hampered, 
efforts are made to define substitute materials to account for the topsoll 
loss in the mining process. The criteria used in the field for determining 
whether topsoll can be removed from a steep slope are based on safety. Dozer 
operators clearing trees are instructed to stop when the conditions are unsafe 
and there is danger of rolling the tractor. Substitute topsoll material is 
used to compensate for the remaining steep areas. For areas in which subsoil 
substitutions are necessary or considered desirable, soil-overburden data are 
again used in a similar manner to demonstrate suitability of the substitute 
materials. 

Considerable soil-overburden data input is required in the permitting of 
the "Special Categories of Mining" defined in the permanent program. For all 
prime farmland areas not covered by grandfather" clauses, detailed characteri- 
zation of the various soil-subsoil relationships is mandatory. Projects 
involving stream relocations in the Midwest comprise category of mining which 
soil-overburden data are used. Detailed studies of relocation routes are made 
in order to identify potential physical or chemical problems. In the West, 
identification of alluvial valley floors (AVF's) and the definition of their 
essential hydrologlc functions requires extensive soil-overburden input. 
Within the last 3 years, two detailed AVF technical reports of streams in the 
West have been completed by the company. 

Permitting — Design of Mining and Reclamation Plans 

For the most part, the soil-overburden resources of an area govern the 
overall objectives of the mining and reclamation plan. Therefore, the most 
important role that baseline data serve in the planning process is a constant 
check and balance of the proposed actions against the mining and reclamation 
objectives. 

For example, in the Midwest, the amount of prime farmland on a given 
property will dictate the soil-overburden handling procedures of a proposed 
operation. In the case of prime farmland, the soil-overburden data are used 
as support information that the proposed mining and reclamation plan will 



29 



return an area to premlne productivity levels. Another good example would be 
the alluvial valley floors (AVF's) in the West. The identified essential 
hydrologic functions of an AVF set the framework for design of a detailed 
reconstruction plan. For an AVF, the baseline data are used as technical 
support for restoration plans for the essential hydrologic functions. 

For both of these examples, the data are used to assess the raining and 
reclamation plan relative to impacts' on the prevailing hydrologic balance. 
Documentation that the proposed action will have minimal impacts on the 
hydrologic balance is required. 

Soil-overburden data provide the technical support for defining selective 
placement needs in mining. Based on the data, selective placement recommenda- 
tions are communicated to planning engineers for consideration in design of 
mining methods and definition of equipment needs. Since selective placement 
(that is, haulback versus direct cast) from a soils or geology standpoint is 
not necessarily the same from a mine feasibility viewpoint, the final deci- 
sions on equipment and mining methods are left to the planning engineers and 
management. However, once the decisions are made and the plans implemented, 
soil-overburden data once again are used in assessing the potential success of 
the selective placement efforts in meeting reclamation goals. 

Waste disposal plans receive considerable technical input in their 
design. The overburden data define the potential acid-or toxic forming mate- 
rials to be encountered during mining. Once the parameters are known, appro- 
priate handling and/or treatment techniques are incorporated into the plans. 

Access road and haulroad construction plans receive attention from the 
standpoint of type of overburden materials considered for use. Attempts are 
made at each mine to define those materials that are suitable for road 
construction. Such information is incorporated into the mine plan. 

Other examples of how soil-overburden data are used in the mining plan- 
ning process are (1) fertilizer and lime recommendations, (2) erosion stabili- 
zation considerations, and (3) water quality assessment of surface drainage 
and impoundments, Textural and clay mineralogy data enable prediction of 
erodibility factors that are used in specific design of various control and 
sedimentation structures (settling basins, culverts, road ditches, terraces, 
etc.). Knowledge of anticipated soil-overburden conditions surrounding a 
proposed water impoundment assists in the prediction of water quality problems. 
Selective placement of acid-forming materials allows prediction of neutral to 
alkaline discharge from the mine property, 

TRACKING OF MINING AND RECLAMATION ACTIVITIES 

Discussions thus far regarding soil-overburden data outline how the infor- 
mation is used in developing comprehensive mining and reclamation plans. The 
ultimate requirement of a plan to demonstrate on paper that the reserve can be 
mined in an environmentally sound manner. However, a very important point 
needs to be made regarding such planning efforts. Detailed soil-overburden 
characterization and comprehensive permit applications are not a panacea for 



30 



the mining industry. They are just tools that can lead to a successful opera- 
tion. The real challange to a coal operator is proper implementation and 
compliance with the plans. 

There exist two basic keys to maintaining an operation in compliance with 
the mining and reclamation plan. The keys are communicating the plan to mine 
personnel and tracking (f ollowthrough) of the raining and reclamation 
activities. Of the two, communication is the more challenging. 

Communication 



Complexity of communication is increasing on a daily basis. The increase 
is the result of rapidly evolving technology and expansion of regulatory con- 
trol of the coal industry. The simplest component of today's overall mining 
and reclamation plan requires a critical path to assure orchestration of the 
total plan. Practically every component of a comprehensive plan involves 
communication of soil-overburden information in one way or another. 

There are three basic audiences to be dealt with in communicating soil- 
overburden issues: (1) Regulatory (State and Federal), (2) company (corporate 
and mine management), and (3) research (university. State and Federal service 
groups). Each group offers its own set of communication challanges. 

Contacts with regulatory personnel range from technical to enforcement 
staff. The main challenges related to soil-overburden issues are (1) to 
obtain clarification and establish agreement on specific requirements of the 
regulations, (2) to provide clear and concise explanations of soil-overburden 
characterization and handling procedures, and (3) to establish and maintain 
technical credibility. Successfully meeting these challenges should generate 
mutual spirit of good faith and cooperation, 

A vital area of communications for industry is with university, State, 
and Federal research organizations. The challenge for all parties concerned 
is twofold. First, a continuum in exchange of ideas to define high-priority 
and practical research needs, as well as methods of study, is paramount. 
Second, dissemination of results and technological developments in a timely 
manner is essential to continued advancement of reclamation efforts, 

Followthrough 

Once communication is made to operational personnel regarding the goals 
and objectives of soil-overburden handling procedures, the real task of follow- 
through of the minning and reclamation plan begins. Throughout the operation 
tracking process, various needs for additional soil-overburden characteriza- 
tion arise. The followup involves routine monitoring of mining progress and 
terminates with sampling of the reclaimed lands for documentation- and bond- 
release purposes, A brief description of tracking activities during the 
actual coal mining process follows. 



31 



Monitoring 

The variability of nature complicates the raining task to a point at which 
reclamation goals can be in jeopardy. Mining under adverse weather conditions, 
especially if continued for any length of time, can result in severe altera- 
tions of mining methods. Such alterations can have an impact on final recla- 
mation objectives. Difference in shift personnel (degree of awareness and 
concern for reclamation goals, work attitudes, job qualifications, etc.) and 
frequent personnel-position changes can also have an impact on the final 
outcome of mining activities. Because of these unpredictable factors, it is 
essential that monitoring should be continued through the life of the 
operation until all bonds are released. 

Since August 1977, a routine monitoring program has been in progress for 
all of AMAX Coal Co.'s midwestern operations. Initially, surveys were con- 
ducted on a monthly basis through the implementation period of OSM's interim 
program. Currently, the surveys are conducted on a quarterly basis. The 
survey covers all phases of each operation. A team consisting of environmen- 
tal, legal, and operations personnel conducts the surveys. Findings of each 
survey are reviewed in depth with mine management, and remedial actions (if 
necessary) are taken to correct potential problems. The monitoring program is 
a very useful tracking and communication tool. Its findings complement plan- 
ning needs (water management, erosion control, revegetation, etc.) of the mine. 

Graded Cast Overburden Assessment 

As a followup to selective placement of overburden materials by major 
stripping equipment, a detailed evaluation of graded cost overburden is made 
prior to topsoil replacement. Selective placement with dragline equipment is 
not a panacea for disposal of undesirable overburden materials,. At times, 
handling or pit conditions result in inconsistent placement practices during 
stripping. It is not uncommon for such materials to be reexposed in the 
reclamation grading process. 

Assessment of graded cast overburden is completed for the purpose of 
defining the suitability of the materials for meeting rooting media require- 
ments. Soil replacement must be coordinated with the land use plan for a 
given area. Sampling efforts seek to define the amount of rock and the 
presence of acid- or toxic-forming materials within the surface of the graded 
cast overburden. Table 1 outlines routine analyses completed on the samples 
collected. Data are used in formulating treatment and/or cover (burial) 
recommendations prior to replacing the topsoil. 

Troubleshooting 

As previously indicated, the unforeseen always arises in surface mining. 
The situation may require immediate investigation to enable continued opera- 
tions, or it may be a problem requiring resolution over a longer period. In 
either case, sufficient soils, overburden, and hydrogeologic data must be gen- 
erated more clearly to define practical solutions to the problem. An example 



32 



of a short-term problem would be an investigation of the soil-clay mineralogy 
relationships to a total suspended solids (TSS) problem at a mine discharge 
point, 

A long-range problem facing all midwestern operations is the reconstruc- 
tion of prime farmland soils. The industry has limited time remaining to 
demonstrate productivity capabilities of mined land to meet prime farmland 
standards of the OSM permanent program. Proposed OSM language of the grand- 
father clause of the prime farmland performance standards sheds light on the 
time frame involved. If the language is adopted, the industry has until 1982, 
At each of our midwestern operations, efforts are being made to evaluate soil 
productivity relative to reconstruction methods. 

Bond Release 

The last phase of tracking relative to soil-overburden and hydrology 
involves preparation and documentation for reclamation bond release. For 
areas reclaimed to prime farmland standards, the replaced soil materials are 
characterized. The information is used in evaluating the need for additional 
subsoil tillage or soil amendments. Such farm-related activities may be 
required to enhance productivity yields of the restored farmlands. Similar 
characterization activities are conducted on all other areas designated for 
various land uases. 

REGULATORY ISSUES AND RESEARCH NEEDS 

There exist several issues concerning provisions of the permanent pro- 
gram that directly relate to the use of soil-overburden data in mine planning 
and operation followthrough. From a data interpretation and field applica- 
tion standpoint, clarifications of the issues are needed. Further technical 
research is needed to enable industry to comply with the intent of the 
P.L, 95-87, For the sake of brevity on the subject, only two major issues 
are addressed here. The issues deal with acid-forming and toxic-forming mate- 
rials. The issue with acid-forming materials is OSM's definition. The con- 
cern for toxic-forming materials is the state-of-the-art of defining toxicity 
levels for soil-overburden materials, 

Acid-Forming Materials 

In the permanent program, acid-forming materials are defined as "earth 
materials that contain sulfide minerals or other materials which, if exposed 
to air, water, or weathering processes, form acids that may create acid drain- 
age" (13) . Technical problems arise with the definition. First, it is too 
general in scope. As the definition reads, practically all overburden of min- 
able coal reserves in the United States can be described as acid forming. 
All overburden, including some unweathered glacial tills, contains a certain 
percentage of sulfide minerals. Most of the same overburden materials, how- 
ever, have sufficient inherent neutralizing minerals (calcite, dolomite, sider- 
ite, etc) to more than counterbalance acids generated by oxidation of exposed 
sulfide minerals. The definition fails to recognize this very important 
asset of overburden materials. 



33 



The second difficulty with the definition lies in the fact that it is 
oriented totally to assessing acid drainage potential and not acid 
revegetation potentials of graded cast overburden (mine spoil) . 

To interpret the meaning of acid forming, one has to refer to the defini- 
tion of acid drainage in the regulations. Acid drainage, the key element in 
the definition of acid-forming materials, is defined as water with a pH of 
less than 6.0 having a total acidity that exceeds total alkalinity. 

Normal agricultural soils contain clay particles and organic matter with 
attached hydrogen ions on exchange sites of the clay-mineral lattice or 
organic complex. The presence of hydrogen on the clay minerals is a product 
of the weathering process. When such clays come in contact with soil mois- 
ture, the hydrogen ions form acids. Depending on the base saturation of the 
soils, agricultural soils can and quite often do have a pH value less than 
6.0. The optimum pH range for growing wheat and corn is 5.5 to 7.5 (4^). When 
the pH of a soil is less than 6.0, does the farmer consider the soil to be an 
acid-forming material capable of creating acid drainage? No, he does not. He 
recognizes that the soil is slightly sour and needs lime treatment to maintain 
a pH of 6.0 for grain crops. 

Just as the native soils contain "other minerals" that can create acids, 
various overburden contains sulfide minerals. But what is lost or missing in 
OSM's definition of acid-forming materials is the important fact that the same 
overburden materials may contain more than ample alkaline minerals to counter- 
balance acids formed on exposure. Or, the sulfide minerals may be present in 
such quantities that the normal ag-lime applications used with soil can be 
used as an amendment to control pH levels at or above 6.0. 

The third issue with the definition and probably the most difficult to 
cope with from an analytic data interpretation standpoint is the inference of 
applying standard water chemistry analysis to assess a solid-state, geologic 
sulfide versus carbonate balance. As written, the definition completely 
ignores all the detailed overburden characterization work of the last decade. 
Over the last 10 years, tremendous strides have been made in defining method- 
ology for assessing the acid-forming potential of overburden. The state-of- 
the-art recognizes the importance of assessing carbonate as well as sulfide 
content of the rocks (8^, 11-12) . The definition on the other hand takes a 
giant step backwards to the early sixties in terms of its analytic approach to 
defining what constitutes acid-forming materials. 

From a field application standpoint, the full realization of the defini- 
tion problem arises when assessing graded cast overburden relative to its 
acid-forming potential as defined by the regulations. Table 3 lists pertinent 
sections of the permanent program that address handling procedures of acid- 
forming materials. If acid-forming materials are exposed in the mining pro- 
cess, they are to be either covered with 4 feet of nontoxic materials or 
adequately treated to neutralize acids generated on oxidation. 

Consider the mine situation where potentially acid-forming overburden is 
mixed with other overburden materials and is exposed in the graded spoil. For 



34 



example, consider the cast overburden where a fourth or less of the graded 
spoil contains rock fragments that by themselves have a slight potential for 
creating acid conditions in the spoil. Because of the inadequacies of the OSM 
definition, uncertainties exist over how one goes about assessing the acid- 
forming potential of such graded cast overburden. Clarification of such mat- 
ters is needed from OSM now. The research completed to date has developed the 
methodology and has practical solutions to the problem at hand. However, OSM 
has repeatedly failed to comprehend the problem with the definition and has 
ignored existing research findings and industry comments as evidenced by its 
maintaining the same definition throughout formulation of the regulations, 

Toxic-Forming Materials 

In the relation to the soil-overburden characterization for purposes of 
making soil and hydrologic impact assessments of a proposed mine operation, 
major concerns exist over the identification and treatment of potentially 
toxic-forming materials. The implications of the term "toxic-forming" the 
coal mining industry are far reaching, especially when one considers the 
state-of-the-art of defining toxic-forming materials within the overburden. 

Recent research efforts by Dollhopf (_3) , Miller (8^), Byrnes (_1 ) , and San- 
doval (10) are helpful to the industry in defining suspect limits or toxicity 
for overburden materials. However, they are only the beginning of a long 
road ahead in defining what elemental and geochemical combinations lead to 
toxic-forming conditions. 

It is one thing to define a suspect limit of a particular trace metal 
in the overburden based solely on percent content in the host rock. It is 
another to understand how that particular metal will react under various geo- 
chemical conditions encountered in mining conditions. Future research efforts 
need to be oriented tov/ards a definition of leachate mobility characteristics 
of various metals under various pH leachate conditions. Hood (6) is conduct- 
ing such research on trace metals associated with dominant coal seams of 
southern Illinois, The results of the studies are directed toward establish- 
ing predictive behavior models of the metals under various physical and 
chemical conditions. 



Another area of research needing immediate attention is that of identify- 
ing the mineralogical phase of potentially toxic-forming trace metals within 
the overburden. Once the mineralological phase is understood, research can 
proceed to establishing detailed geochemical solute-solution relationships 
between overburden (spoil) and ground water (reestablished). Solution equilib- 
ria, ion exchange, and mineral resolution rates will ultimately be factors to 
consider when making predictions and completing impact assessments of a pro- 
posed operation on the hydrologic balance of an area. Recent research con- 
ducted by Reifenstein and Krothe (9) reflect the type of work involved in 
completing such an assessment. 

Lastly, research efforts in the area of improving mining methods to 
achieve total reclamation objectives must keep pace with the findings of the 



35 



analytic research. Analytic research to define toxic-forming materials should 
always have as a basic objective the goal of practical application to the 
mining station, 

CONCLUSION 

Today's surface mine regulations require detailed soil-overburden charac- 
terization prior to mining. The information is used in generating environmen- 
tally sound mining and reclamation plans. Planning is only half the battle. 
The real challenge lies in followthrough of the plans during mining and recla- 
mation. Throughout the mining process, soil-overburden data are relied upon 
as supportive information for planned actions. 

The key to achieving desired mining and reclamation goals lies in success 
of communication and tenacious followthrough during development of the coal 
reserve. Because of the ever-increasing complexity of surface mining today, 
it is going to take a cooperative effort of industry, university, and 
regulatory personnel to meet the mandate of the law to 

assure that the coal supply essential to the Nation's energy 
requirements, and to its economic and social well-being is provided 
and strike a balance between protection of the environment and agri- 
cultural productivity and the Nation's need for coal as an essential 
source of energy. 

Advances in practical technology are urgently needed to meet the chal- 
lenges set forth in the act. The basic foundation for such technological 
advance will always be the dictates of the soil, overburden geology, and 
hydrology resources of any given coal reserve. 

Comments and Questions from the Floor 

Dr, Richard Barnhisel , Comment on the definition of fragipan as a limit- 
ing layer: I am sure that a true fragipan is a limiting layer in situ as a 
natural body. Roots may penetrate in parts of these horizons. However, this 
is a function of the present chemical and physical properties. If large lime 
rates are used, this material may become usable material. Without treatment, 
this horizon may be considered as being toxic. 

Response ; We concur with Dr. Barnhisel that the fragipan does present a 
limiting layer to plant root development. The low pH and high aluminum com- 
bined with low phosphorus availability restricts root growth. A few roots may 
follow a crack between peds in search of better soil beneath the fragipan, but 
the value they receive from the fragipan is negligible. Thus, a fragipan 
should be considered a limiting layer in soils. 



36 



REFERENCES 

1. Byrnes, W. R. , W, W, McFee, and J, G. Stockton. Properties and Plant 

Growth Potential of Mineland Overburden. U.S. EPA Ind. Envir. Res. 
Lab., Office of Res. and Develop., SEA-CR lAG No. 624-15-18, 1980 (in 
press). 

2. Caruccio, F. T., J. C. Ferm, and J. C. Home. Paleoenvironment of Coal 

and Its Relation to Drainage Quality. U.S. EPA (Cincinnati, Ohio). 
Final Rept. U.S. EPA-600/7-77-067, 1967, 90 pp. 

3. Dollhopf, D. J., J. D, Goering, C. J. Levine, B, J. Bauman, and R. L. 

Hodder, Selective Placement of Coal Stripmine Overburden in Montana. 
Montana Agr. Exp Sta., Montana State Univ., 1979, p. 55. 

4. Foth, H. D. Fundamentals of Soil Science. John Wiley & Sons, New York, 

6th ed., 1978, p. 210. 

5. Hester, N. C, and S. S. Leung. The Prediction of Sulfur in Coal-Bearing 

Rocks: Its Bearing on Reclamation. Eastern Kentucky Univ., Dept. of 
Geology (Richmond, Ky.), Inst, for Min. and Miner. Res. Contract 
201-65-98903-53485; draft final report available from Kentucky 
Institute for Mining and Mineral Research. 

6. Hood, W. C. Predicting Mine Effluent and Ground Water Quality Prior to 

Mining, 111. Min. and Miner. Resources Res. Inst., Southern 111. 
Univ., Carbondale, 111.; available from author. 

7. Horne, J. C, and J. C. Ferm. Carboniferous Depositional Environments in 

the Pocahontas Basin; Eastern Kentucky and Southern West Virginia. 
Field Guidebook, Dept. of Geol. , Univ. of South Carolina, Columbia, 
S.C., 976, 129 pp. 

8. Miller, C. J., and others. Suggested Guidelines for Method of Operation 

in Surface Mining of Areas With Potentially Acid-Producing Materials. 
6th Symp. on Surface Coal Mining and Reclamation, Coal Conf. & Expo V, 
Louisville, Ky., Oct. 23-25, 1979. McGraw-Hill, Inc., New York, 1979, 
pp. 177-197. 

9. Reifenstein, M. B., and N. C. Krothe. The Ground-water Chemistry of the 

Carbondale Group, Southwest Indiana. Abstracts, North-Central Sec, 
Geol. Soc. of America, v. 12, No. 5, 1980, p. 264. 

10. Sandoval, F. M. , and J. F. Power, Laboratory Methods Recommended for 

Chemical Analysis of Mined-land Spoils and Overburden in Western United 
States, U.S. Dept, Agr,, Agr. Handbook 525, 1977, 31 pp. 

11. Smith, R. M. , A. A. Sobek, T. Arkle, Jr., J, C. Sencindiver, and J. R. 

Freeman. Extensive Overburden Potentials for Soil and Water Quality. 
U.S. EPA (Cincinnati, Ohio), Protection Technology Series, 
EPA-600/2-76-184, 1976, 310 pp. 



37 



12. Sobek, A. A., W, A, Schuller, J. R. Freeman, and R, M, Smith, Field and 

Laboratory Methods Applicable to Overburdens and Minesoils. U.S. EPA 
(Cincinnati, Ohio), EPA/2-78-054, 1978, 204 pp. 

13. U.S. Code of Federal Regulations. Surface Coal Mining and Reclamation 

Operations Permanent Regulatory Program. Federal Register, v. 44, 
No. 50, Mar. 13, 1979, 91 Stat. 475-503. 

14. U.S. Congress, Surface Mining Control and Reclamation Act of 1977. 

Public Law 95-87, Aug. 3, 1977, 91 Stat. 475-503. 



38 



MINESOIL CLASSIFICATION 
by 
E. S. Lyle, JrJ 



ABSTRACT 

This paper describes 11 minesoil classification systems that have been 
developed for coal surface mines in the Eastern United States, It is con- 
cluded that the most useful method of minesoil classification would be one 
that was based on the Soil Conservation Service system of soil taxonomy. This 
would provide a means of minesoil classification that would be understood by 
many soil scientists in the United States. Such a classification could be 
used for minesoil revegetation and erosion control at present and could be 
modified for practically any other future use. 

INTRODUCTION 

According to early Chinese records, an engineer named Yu classified soils 
on the basis of color and structure about 4,000 years ago. Apparently, man 
has always had a passion for classifying everything, and there is a good rea- 
son for this. In order to understand and use complex things we need to clas- 
sify them. If this is true, the classification of soils seem quite reasonable 
since soils are certainly complex. 

Two terms or concepts used extensively in soils work are soil taxonomy 
and soil classification. These two terms should be clearly delineated and 
understood. Soil taxonomy is the classification of soils in terms of their 
natural characteristics, such as ones caused by climate, soil water, topog- 
raphy, and mineralogy. A good taxonomy system would allow soils to be placed 
in groups according to similar characteristics. Soil classification includes 
taxonomy, but a classification would use the taxonomy system to group the 
soils for some particular purpose; for example, agriculture, road building, or 
lake construction. To accomplish this purpose, grouping or subdividing some 
of the taxonomic classes would be required. 

The Soil Conservation Service manual on Soil Taxonomy (10)^ says: "Clas- 
sifications are contrivances made by men to suit their purposes. Classifica- 
tions are not truths that can be discovered." They also say that a perfect 
classification would have no drawbacks when used for the purpose intended, and 
in order to best serve each different purpose, a different classification is 
required. Thus, the value of any minesoil classification system must be 
judged in relation to the purpose for which it was intended. In most cases, 

^Associate professor. Department of Forestry and Agricultural Experiment Sta- 
tion, Auburn University, Auburn, Ala. 

^Underlined numbers in parentheses refer to items in the list of references at 
the end of this paper. 



39 



the minesoil ciassif i'^ation schemes developed in the United States were 
Intended to aid revegetatlon. 

Information on the plant-growing characteristics of the minesoil, which 
plants will grow best on the minesoil, and what procedures give fast and com- 
plete minesoil cover Is required for any successful reclamation program. 
This paper addresses the first piece of Information needed; that Is, the 
plant-growing characteristics of the minesoil. 

Much of the previous work on minesoil classification was done before the 
Federal Reclamation Act of 1977 and dealt with a mixture of soil and geologic 
horizons that the miner left for the reclaimer. This Is no longer the situa- 
tion. Now, the original surface soil must be replaced on top of a mixture of 
soil and geologic materials, or the original soil horizons may be replaced in 
nicely compacted layers; this results in a different type of minesoil, and the 
older classifications may no longer be useful. 

PRESENT MINESOIL CLASSIFICATION AND TAXONOMY 

One of the earliest (1948) minesoil classifications, (11) (table 1) clas- 
sified minesoils for revegetatlon purposes into three acidity or reaction 
classes: (1) Very strongly to strongly acid (2) moderately to slightly acid, 
and (3) calcareous. The classifiers were concerned with forage species reveg- 
etatlon. In that same year, Llmstrom (3) published a classification system 
for reforesting surface mines in the Central States (table 2), based on acid- 
ity classes, texture classes of the soil material, and percent of the surface 
minesoil made up of soil-sized particles. 

TABLE 1 . - Minesoil classification in 1948 by E. H.Tyner, 
R. M. Smith, and S. L. Galpin for grasses 
and legumes In West Virginia (11) 

Class Acidity 

A Very strongly acid (numerous wet spots). 

B Moderately to slightly acid, 

C Calcareous . 



40 



TABLE 2. - Mlnesoil classification in 1948 by G. A. Llmstrom 
for trees in Ohio, Indiana, Illinois, Missouri, 
Arkansas, Oklahoma, Iowa, Kansas, 
and Kentucky (3) 



Class 



Characteristics 



ACIDITY 



1, 
2. 
3. 

4. 

5. 

T. 

B. 
C. 



Toxic (more than 75 percent of area < pH 4.0), 
Marginal (50 to 75 percent toxic). 
Acid (more than 50 percent with pH 4,0 to 6,9), 
Calcareous (more than 50 percent with pH 7,0 or 

higher) , 
Mixed (approximately same proportion of toxic acid 

and calcareous areas). 



TEXTURE 



Sands: to 50 percent soil material on surface, 

51 to 100 percent soil material on surface. 
Loams and silty shales: to 40 percent soil 

material on surface, 

41 to 100 percent soil material on surface. 
Clays: to 30 percent soil material on surface, 

31 to 100 percent soil material on surface. 



Acidity has been the basis of all minesoil classification systems pro- 
posed since 1948; many also used stoniness, color, and texture. Hart (2) used 
origin of the stone fragments in the minesoil, color, acidity, and structure 
of the minesoil to classify minesoils for tree planting in the bituminous 
region of Pennsylvania (table 3). Smith (8) used acidity, stoniness, and 
slope to classify Ohio minesoils for grass, legume, and tree revegetation 
(table 4), In this case, stoniness was apparently used to distinguish between 
areas that could not be worked with machinery. The very stony and extremely 
stony classes were reserved for woodland and wildlife. In 1965 a minesoil 
classification system based on acidity, slope, and stoniness was developed for 
Pennsylvania by a research committee (6) (table 5), This system allowed for 
different acidities within a minesoil class, and stoniness was used to divide 
areas into tillable and nontillable, Medvick (_5) developed a system for tree 
planting in Indiana in 1969 (table 6). This system classified minesoils 
according to texture and acidity. A different mixture of tree species is rec- 
ommended for each minesoil class. Acidity, slope, and stoniness were used 
also by the West Virginia Department of Natural Resources (11) to classify 
minesoils for grass, legume, shrub, and tree planting (table 7). The stoni- 
ness classes were used to classify minesoils into tillable, nontillable, and 
unsuitable for tree seedling planting. In 1973, the Soil Conservation Ser- 
vice ( 12) developed a classification scheme for Kentucky based on acidity, 
stoniness, particle size, and slope (table 8). This scheme used combinations 
of stone content, soil particle content, and specific particle sizes in the 
classification. 



41 



TABLE 3 . - Mlnesoll classification by G. Hart and W. R. Byrnes 
for trees in the bituminous coal region 
of Pennsylvania (3) 

Bank type I : 

Origin Carbonaceous ( slaty) shales . 

Color Dark gray. 

Acidity pH 2.5 to 3.5. 

Structure Loose material. 

Weathering. Weathers slowly. 

Bank type II: 

Origin Predominantly shale with lesser 

amounts of shale. 

Color Yellow to brown. 

Acidity pH 4.0 to 5.5. 

Structure Compact material. 

Weathering ,,, Weathers fairly rapidly. 

Bank type III: 

Origin Predominantly sand and sandstone with 

lesser amounts of shale. 

Color Light yellow to rusty brown. 

Acidity pH 4.0. 

Structure Loose material. 

Weathering , Weathers slowly. 

Bank type IV: 

Origin Predominantly glacial till . 

Color Pale yellow. 

Acidity pH 4.5 to 5.0 or pH 8.0. 

Structure Very loose material when moist (crusty 

wheq dry). 

Weathering Weathered. 



42 



TABLE 4. - Mlnesoll classification In 1962 by H. G. Smith, H. H. Morse, 
G. E. Bernath, L, E. Glllogly, and W. M. Brlggs for 
for grasses, leguiues, and trees In Ohio (8) 



Stonlness 



Slope and use by stonlness grouping 





ACIDITY 


CLASS I.— 75 PERCENT OF MINESOIL HAS pH 5.5 OR 


GREATER 


A 


Nonstony (topsoll replaced, no stone on surfac 
Slope Use 

1. to percent Cropland 

2. 6 to 12 percent Cropland 

Stony (no topsoll, most stones removed, stone 
In diameter) 

1. to 6 percent Hayland 

2. 6 to 18 percent Hayland 

Stony (stones not removed, stone <4 Inches In 

3. to 18 percent Pasture 

Very stony (stones >4 Inches In diameter) 

3. to 18 percent Woodland 

Extremely stony (mlnesoll surface covered In j 

4. All slopes VJlldlife 


-e) 


B 


<4 Inches 


C 


diameter) 


D 




E 


jtone) 





ACIDITY CLASS II.— <75 PERCENT OF MINESOIL > pH 5.5, 
BUT AT LEAST 75 PERCENT > pH 4.5 



c 


Stony 

3. to 18 percent 






Pasture 


D 


Very stony 

2. 6 to 18 percent 






Woodland 


E 


Extremely stony 

5. >18 percent 






Wildlife 



ACIDITY CLASS III.— 50 PERCENT OF MINESOIL OR MORE > pH 4.5, 
BUT NOT MORE THAN 50 PERCENT > pH 4.0 



C and D. 



Stony and Very stony 
4. All slopes 



Woodland 



ACIDITY CLASS IV.— >50 PERCENT OF MINESOIL >pH 4.0 



C, D, and E, 



Stony, Very stony, and Extremely stony 
4. All slopes Wildlife 



43 



TABLE 5 . - Minesoll classification in 1965 by the Research Committee 
of Coal Mine Spoil Revegetation in Pennsylvania 
for grasses, legumes, shrubs, and trees (6) 



Class 



Characteristics 



ACIDITY 



A, 
B, 

C, 

Ri 

T, 
jj 

a. 
b. 



75 percent or more of minesoll above pH 5.5, and not more 

than 25 percent of area below pH 4.0. 
Less than 75 percent of minesoll above pH 5.5, but at 

least 75 percent of area above pH 4.5, and not more than 

25 percent of area below pH 4.0. 
More than 50 percent of minesoll below pF 4.5, but not 

more than 50 percent below pH 4.0. 
More than 50 percent of minesoll below pH 4.0. 



SLOPE 



Level to steep (0 to 25 percent). 
Very steep (>25 percent). 



STONINESS 



Nonstony (tillable). 

Very stony (cannot till but can plant trees by hand) 



TABLE 6 . - Minesoll classification in 1969 by C. Medrlck 

for trees in Indiana (5) 



Texture 


Acidity 


Trees to plant 


I — Nonsandy 

II — Sandy 

II — Sandy 


A — pH 5.5 or greater 

B — pH 4.0 or greater 

C — pH 4.0 or below 


20 percent northern red oak, etc. 
40 percent white pine, etc. 
33-1/3 percent pitch pine, etc. 



TABLE 7 . - Minesoll classification in 1971 by West Virginia 
Department of Natural Resources for grasses, 
legumes, shrubs, and trees (13) 



Class 


Characteristics 


ACIDITY 


I 


pH 5.5 and greater. 
pH 4.0 to 5.5. 
pH <4.0. 


II 


Ill 


SLOPE 


A 


Gentle (0 to 10 percent). 

Moderate to steep (10 to 45 percent). 

Extremely steep (>45 percent). 


B 


C 


STONINESS 


1 


Nonstony (tillable). 
Stony (cannot till). 
Extremely stony (cannot hand plant with seedlings). 


2 


3 



44 



TABLE 8 . - Mlnesoll classification In 1973 by Soil Conservation 

Service for grasses, legumes, shrubs, 
and trees in Kentucky (12) 



Class 



Characteristics 



X • • • • 

II 

III.... 

IV.... 



A. 
B. 
C. 

T. 

2. 

3. 

4. 

5j 

a. 
b, 
c. 



ACIDITY 



Alkaline and calcareous (pH >7.3), 
Medium acid to alkaline (pH 5.6 to 7.3) 
Acid (pH 3.6 to 5.5). 
Extremely acid (pH <3.6) . 



STONINESS 



Nonstony (<0.01 percent stones and boulders). 
Stony (0.01 to 15.0 percent stones and boulders). 
Very stony (15.0 to 50.0 percent stones and boulders) 
Very stony (>50.0 percent stones and boulders). 



PARTICLE SIZE 



Fragraental (90 percent or more stone, <10 percent 

soil) . 
Skeletal (35 to 95 percent stone, 10 to 65 percent 

soil, <18 percent clay), 
Sandy (<35 percent stone, 35 to 100 percent sand and 

loamy sand) . 
Loamy (<35 percent stone, 35 to 100 percent very fine 

sand loam, very fine sand, and <35 percent clay). 
Clayey (<35 percent stone, 35 percent or more clay). 



SLOPE 



Nearly level to moderately steep (0 to 30 percent). 

Steep (30 to 70 percent). 

Very steep (<70 percent). 



Two publications from West Virginia University (_7, _9) describe a taxonomy 
system based on the Soil Conservation Service (SCS) system (table 9). The 
West Virginia work used an order from the SCS system, but developed new names 
for the rest of the classes and suggested a new suborder called spolents, 
Spolents would include manmade soils such as minesoils. The next class would 
be a great group named udspolents which means spolents occurring in a humid 
region. This region would include all of the Eastern U,S, coalfields. New 
subgroup and family names for West Virginia minesoils were also developed. 
Series names were not suggested because mlnesoll properties changed too 
rapidly for at least the first 10 years after revegetation. This West 
Virginia scheme has the advantage of being based on principles used and under- 
stood by thousands of agronomists and soil scientists. In addition to nation- 
wide application it also has the advantage of being useful for classifying 
soils for purposes other than revegetation, such as building sites, wildlife, 
erosion, and recreation. It has the disadvantage of being a taxonomic system 
rather than a classification system. To make direct use of this system, more 
work would have to be done to place minesoils in groups for a useful purpose 
such as revegetation. 



45 



TABLE 9. - Minesoil taxonomy in 1974 by J. C. Sencindiver (7_) 

and R. M. Smith (9) for all planTs 
in West Virginia 

Order Entisol (recent soils). 

Suborder Spolents (manmade soils). 

Great group Udspolents (spolents occurring in a humid region). 

Subgroups Fissle (shale). 

Plattis (sandstone). 

Regolithic pattic (sandstone, chroma > 2). 

Carbolithic (coal, dark shales and mud, value of 3 or less). 

Schlickig (silt and clay). 

Typic (mixture of subgroups). 
Family Determined texture, mineralogy, acidity, and soil temper- 
ature class). 

Series Determined texture, color, mottling, structure, horizons, 

and pocket inclusions. 

Soil Classification Purposes 

1. Engineering 7. Sanitary facilities 

2. Permeability 8. Building sites 

3. Available water capacity 9. Construction material 

4. Acidity 10. Crops and woodland 

5. Shrink-swell potential 11. Wildlife 

6. Erosion 12, Recreation 

The SCS has also classified some minesolls under its system in at least 
two States, Two soil series have been established in Alabama. The Palmerdale 
series is classified as a loamy, skeletal, mixed, acid, thermic family of 
Typic Udorthents; Brilliant soil is the same except that it is nonacid. These 
soils are classified under the order of Entisols, suborder of Orthents, great 
group of Udorthents, and subgroup of Typic Udorthents. 

Wood (14) concludes that this classification is undesirable for minesoils 
since it tends to become a depository for groups of unrelated types that 
should not be classified together. He believes that minesoils should be clas- 
sified as Arents under the order Entisols, Wood proposes that a great group 
named Udarents be created for north Alabama, Typic Udarents would be Udarents 
with fragments of former horizons in their profiles, Udarents without frag- 
ments of former horizons would be Litoclastic Udarents if there were less than 
50 percent soil-sized particles and Pedoclastic Udarents if there were more 
than 50 percent soil-sized particles. 

In Ohio, Hall (1) used the SCS system but went directly to the series 
level and classified five minesoil series on the basis of their acidity, 
stoniness, and texture (table 10). More minesoil characteristics probably 
would have to be evaluated in order to classify minesoils for revegetation. 
Table 11 shows a minesoil classification system developed for Alabama in 1979 
by Lyle ( M • This system is based on minesoil acidity, stoniness, and color. 
Only five different classes were found, but the system allows for the 



46 



Inclusion of any other minesoils that may occur. Limestone and fertilizer 
recommendations are given for each of the five minesoils. 

TABLE 10. - Minesoil taxonomy in 1977 by G. F. Hall for Belmont 

and Noble Counties in Ohio (1)^ 

Morristown Silty clay loam, pH 7.7, 12 percent stone, 

Fairpoint Silty clay loam, pH 7.7, 16 percent stone, 

Bethesda... Loam, pH 3.9, 37 percent stone. 

Barkcamp Loamy sand, pH 3,8, 26 percent stone, 

Enoch Clay, pH 2.7, 13 percent stone. 

^U.S, Survey Classification System; soil series determined by 

texture , color, mottling, structure, acidity, consistence, 

mineralogy, salt content, humus content, 

TABLE 11. - Minesoil classification in 1979 by E. S. Lyle, 
P. A. Wood, and B. F. Hajek for grasses 
and legumes in Alabama (A) 



Class 



Characteristics 



STONINESS 



I, 
II, 

T7, 
B.. 

T7. 

2.. 
3.. 
4.. 



More than 50 percent of particles >2mm in diameter. 
More than 50 percent of particles <2 mm in diameter. 



COLOR 



Dark (Munsell color value of soil fraction <4 when noist). 
Light (Munsell color value of soil fraction >4 when moist) 



ACIDITY 



Alkaline (pH >7.5). 

Near neutral or neutral (pH 5.5 to 7.5). 

Very acid (pH 3.5 to 5.5). 

Extremely acid ( pH <3. 5 ) . 



FUTURE MINESOIL CLASSIFICATION 



Most of the preceding classification systems are designed for minesoils 
without horizons that were created haphazardly by overburden removal and 
regrading. An exception is the system proposed by Smith (9). There is no 
reason why this system could not be modified and used for all minesoils 
created under the 1977 Federal Reclamation Act. When reclamation is done 
according to Office of Surface Mining regulations it is possible to create a 
minesoil with 6 inches of acid surface soil and an alkaline subsoil. Under 
these circumstances we need to be sure to use plant species that can utilize 
the alkaline subsoil. The amendment recommendations from existing classifica- 
tion schemes can probably be used to ameliorate undesirable subsoil material. 
It is possible that the use of present knowledge about minesoil plus informa- 
tion about the surface soil from soil testing laboratories can result in a 
completely adequate revegetation project in most rained areas. However, it 
seems more likely that a nationwide classification system would be more useful 
over a long period of time. 



47 



Plant Growth and Soil Erosion Factors 

Classification schemes are usually developed in order to carry out some 
objective — in this case revegetation of the minesoil and control of minesoil 
erosion. The soil factors that control plant growth and degree of soil ero- 
sion must then be considered. Water is the factor that plays the greatest 
role in both revegetation and erosion control. Texture, structure, organic 
matter, soil depth, stoniness, and slope all play important parts in determin- 
ing the amount of soil water available for plant growth. Most minesoils will 
have no structure and little organic matter. Structure will be destroyed by 
removing and replacing the surface soil, and most of the organic matter will 
be lost when the vegetation is removed prior to surface soil removal. Texture 
will vary greatly in both surface soil and subsoil. Stoniness will also vary 
greatly in the subsoil but probably not in the surface soil. 

The depth of minesoils will be almost unlimited unless compaction or 
extreme stoniness causes some limitation. Slope will vary greatly according 
to the original topography. Another factor, minesoil compaction, must be con- 
sidered in order to evaluate any classification system that deals with vegeta- 
tion and erosion control. Several studies have shown that minesoil compaction 
reduces plant growth. Compaction retards water filtration into the soil, 
reduces the water storage capacity of the soil, reduces soil aeration, and 
restricts root development. However, this same compaction will, almost 
certainly, reduce initial soil erosion. 

Nutrient supply is another factor to take into account for revegetation. 
The knowledge gained thus far from working with mixed minesoil materials will 
be useful for making soil amendment recommendations for the manmade subsoils. 

Acidity is one factor that usually occurs when working with surface soils 
and minesoils in the East, However, testing laboratories have many years of 
experience with this problem, and pH adjustment of surface soils should 
present no difficulty, 

Minesoil Factors To Be Considered 

Having identified the soil factors affecting plant growth, the informa- 
tion needed in a minesoil classification system can be obtained. There are at 
least two distinct horizons that will be involved with plant growth. The sur- 
face soil will be the first horizon, and the mixture of overburden material 
beneath this surface will be the second horizon. Since pH has been the most 
consistent factor used in minesoil classification, pH readings on both these 
horizons will be needed. Plant roots will make extensive use of both horizons, 
and the horizons may differ by as much as three pH units. In the case of 
prime farmland reclamation, the pH of all horizons that are penetrated by 
roots will be required. 

Texture is the second soil factor to be considered; again, the textures 
of the surface soil and the subsoil are required. These two horizons could 
differ greatly, with a sand on the surface and a tight clay in the subsoil, 
which could have a tremendous effect on plant growth. 



48 



The next soil factor that should be evaluated is stoniness. There should 
be little stone in the surface soil, but the subsoil could be practically all 
stone. A subsoil that is predominantly stone will have a reduced capacity for 
water storage. 

Slope would also be taken into account. It has been found that steepness 
of slope, shape of slope, position on the slope, and direction in which the 
slope faces all affect tree growth. Of course, slopes also have a tremendous 
effect on use of equipment and on erosion. 

Compaction is the final factor that should be considered in a minesoil 
classification. It appears that the reclaimed surface soils will be compacted 
to some degree to a loss of structure during removal and compaction by equip- 
ment in the process of replacement. This compaction in the surface soil and 
subsoil will reduce both the amount of water that moves downward into the 
minesoil and the total amount of water held by the soil. Other detrimental 
effects of compaction are the restriction of root growth and air movement 
throughout the minesoil mass. 

The other great concern in reclamation is minesoil erosion control. Four 
of the five factors discussed are directly concerned with erosion. Texture of 
the surface soil is one of the principal factors in the Universal Soil Loss 
Equation. Stoniness of the surface soil could have a significant effect on 
erosion, but it is unknown how many of the surface soils will contain stones 
when reclaimed under OSM regulations. The effects of slope steepness and 
slope length on erosion are well known. Compaction is a two-sided factor. 
Compacted soils do not erode as easily as loose soils. Therefore, compaction 
could be a critical factor in erosion control during the period when vegeta- 
tion is becoming established. On the other hand, compacted soils do not allow 
ready infiltration of water into the soil. Instead, the water moves over the 
surface of an unvegetated soil and increases the liklihood of ersion. 

CONCLUSIONS 

Minesoil classifications developed prior to passage of the Federal Sur- 
face Mining Act were probably good ones and useful for the areas and the pur- 
poses for which they were developed. However, the Federal law tends to make 
reclamation practices uniform in all States. Under these circumstances, it 
seems reasonable to have a classification system that covers all the United 
States. Such a taxonomic system within the SCS system already exists, and R. 
Smith and his group and Hall have provided a start in this direction (tables 9 
and 10). An advantage of the SCS taxonomic system is that the soil factors 
used to differentiate between soils can be used to evaluate soils for purposes 
other than revegetation such as building sites, recreation, construction mate- 
rials, sanitary landfills, pond reserviors, roads, and several other purposes. 
Many of the soil characteristics used for revegetation and erosion control 
planning would also be used for these purposes, and any additional character- 
istics needed could be fitted into the overall taxonomic system. Another 
advantage is the fact that a great number of people are already trained in the 
use of this system; with a little additional training these people could 



49 



easily classify minesoils. Classifications done by these trained people would 
be comparable from one State to another and would enhance national minesoil 
research. 

All of the soil factors mentioned are in the SCS taxonomic system or 
could be included as required for minesoil reclamation. The information con- 
cerning some of the factors might have to be gathered in a different way, and 
the classes of soil would almost certainly have to be grouped and subdivided 
differently for revegetation and erosion control. 



50 



REFERENCES 

1. Hall, G. F. Classification of Five Types of Strip Mine Spoil and Impli- 

cations for Reclamation, 5th Symp. on Surface Min. and Reclamation, 
Louisville, Ky., Oct. 18-20, 1977. National Coal Association, Washing- 
ton, D.C., 1977, pp. 1-3. 

2. Hart, C, and W. R. Byrnes. Trees for Strip Mined Land. U.S. Forest 

Service, Northeastern Forest Exp. Sta. Paper 136, 1960, 33 pp. 

3. Limstrora, G. A. Extent, Character, and Forestation Possibilities of Land 

Stripped for Coal in the Central States. U.S. Forest Service, Central 
States Forest Exp. Sta. Tech, Paper 109, 1948, 79 pp. 

$. Lyle, E. S., P. A. Wood, and B. F. Hajek. Classification of Coal Surface 
Mine Soil Material for Vegetation Management and Soil Water Quality. 
Intra-agency Energy-Environment Res. and Dev. Program Rept. to U.S. EPA 
(Cincinnati, Ohio), EPA-600/7-79-123, 1979, 42 pp, 

5. Medvick, C, Selecting Plant Species for Revegetating Surface Coal Mined 

Lands in Indiana, Ch, in A Forty-Year Record in Ecology and Reclama- 
tion of Devastated Land, ed, by R. J. Hutnik and G. David. Gordon and 
Breach, Inc., New York, 1969, pp. 65-80. 

6. Research Committee on Coal Mine Spoil Revegetation in Pennsylvania. A 

Guide for Revegetating Bituminous Strip-Mine Spoils in Pennsylvania. 
State of Pennsylvania, Dept. of Environmental Res., 1971, 46 pp. 

7. Sencindiver, J. C, and R. M. Smith. Proposed Scheme for Classification 

and Mapping of Minesoils. W. Va. Univ., Div. of Plant Sci., Morgantown, 
W. Va., 1974, 44 pp. 

8. Smith, H. G. , H. H. Morse, G. E. Bernath, L. E. Gillogly, and W. M. 

Briggs. Classification and Revegetation of Strip-Mine Spoil Banks. 
Ohio J. Sci., V. 64, 1964, pp. 168-175. 

9. Smith, R. M. , W. E. Grube, T. Arkle, and A. Sobek. Mine Spoil Potentials 

for Soil and Water Quality. Nat. Envir. Res. Center, Office of Res. 
and Dev., U.S. EPA (Cincinnati, Ohio), EPA-670/ 2-74-070, 1974, 302 pp. 

10. Soil Survey Staff, U.S. Department of Agriculture. Dept. of Agr. Soil 

Taxonomy. U.S. Handbook 436, 1975, 754 pp. 

11. Tyner, E. H. , R. M. Smith, and S. L. Galpin. Reclamation of Strip-Mined 

Areas in West Virginia. J. Am. Soc. Agron. , v. 40, 1948, pp. 313-323. 

12. U.S. Department of Agriculture. Kentucky Guide for Classification, Use 

and Vegetative Treatment of Surface Mine Spoil. Soil Conservation 
Service, 1973, 31 pp. 



51 



13. West Virginia. West Virginia Surface Mining Reclamation Regulations. 

Dept. of Nat. Res., 1971, 36 pp. 

14. Wood, P. A. Characteristics, Comparisons, Classifications, and Erodi- 

bility of Some Northern Alabama Coal Mine Spoils. Ph.D. Dissertation, 
Auburn, Ala., 1979, 168 pp. 



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